The challenging mind purification process deriving from intense serious yoga and meditation practice is neither good nor bad.
If the truth of something is 'good', then everyone who experience that something will all have the same 'good' reaction towards that something 'good'.
If the truth of something is 'bad', then everyone who experience that something will all have the same 'bad' reaction towards that something 'bad'.
If the truth of something is just what it is, where it's neither good nor bad, but based on different people have different understanding and limitation, everyone who experience that something will have their own subjective personal reaction towards that something. For the same thing, some will react in a good way, where they think, feel and judge that it's something good. While some will react in a bad way, where they think, feel and judge that it's something bad.
For example, the existence of medicine. Medicine is neither useful nor useless, neither good nor bad. It serves a particular purpose to counter certain illness in certain way. Some people react in a good way towards taking a particular medicine and are getting better from taking that medicine, while some other people react in a bad way towards taking the same medicine and are not getting any better but might be getting worst from taking that medicine. The truth of that medicine is that it's neither good nor bad. If it's really something good, then everyone who take that same medicine will react in a good way without any bad reaction. If it's really something bad, then everyone who take that same medicine will react in a bad way without any good reaction at all.
It's the same as any kinds of names and forms, of different objects and activities that all and everyone might come in contact with and experience.
The co-existence of certain venomous insects or animals in our surrounding living environment, are neither something good nor bad. It's about whether people can find their own way to either live in a space free from any venomous insects or animals, or they can learn how to make some adaptation and adjustment to be able to live in an environment sharing the living space with some venomous insects or animals.
The intense prolonged silent meditation practice and the mind purification process is just what it is. It's neither something good nor bad, even when one of the common effect of the prolonged silent meditation practice where the mind is being restrained from its usual behavior habit would ignite intense mind purification process that might appear to be 'painful' and 'confusing' for many passionate egoistic minds.
Some people who have developed certain degrees of dispassion and non-attachment will know how to confront with any challenging names and forms, and go beyond all those challenging purification process, being undetermined or unaffected by the purification process, and attaining greater 'understanding' beyond the limited understanding or egoistic reaction of the conditional thinking mind. While some people don't have the basic foundation of dispassion and non-attachment, where they don't know how to go beyond those challenging purification process, and are being determined, affected and over-whelmed by the challenging 'painful' and 'confusing' purification process, as these minds are still being conditioned very much by the limited understanding and egoistic reaction of the conditional thinking mind functioning under the influence of certain worldly egoistic thinking and belief.
It's not the responsibility of the meditation practice for how people react differently towards the effect of the practice, where some people have good reaction while some people have bad reaction upon going through the similar degrees of purification process. It's how different minds with different state of mind that come with different understanding and reaction or behavior pattern react differently towards the effect of the intense silent meditation practice.
Those who are suffering from depression, or clinical mental illness, or hallucination, or intoxication addiction, are not allowed to attend intense silent meditation retreat. While there might be many people are not aware of themselves are suffering from certain degrees of mental illness, as they can still live everyday life having a 'normal' social life of family and friends.
While going through intense mind purification process can either free the mind from ignorance and suffering deriving from ignorance, not to say, all kinds of mental blockage practically under the correct understanding with the practice of dispassion, non-attachment, non-identification and non-association, or it would trigger unexpected mental/emotional breakdown, which is common and healthy on the path of yoga and meditation, but for the worldly passionate minds, it can be over-whelming and disturbing, and hence, it's being seen as something bad, wrong, unhealthy and mad. These minds would put the blame onto the practice of silent meditation practice as the cause of their physical/mental/emotional discomfort and pain due to the mind purification process. The minds that have correct understanding will understand that all discomfort and pain during the purification process is just an inevitable process that everyone has to go through by oneself on the path of yoga and meditation.
It's like to eradicate 'cancer growth' from the physical body, the operation procedure of removing the cancer growth is inevitable, but the process of the operation where the body is being cut open exposing flesh and blood, and the look of the cancer growth might appear to be disgusting and painful for many people.
Intense serious silent yoga and meditation practice is sort of like performing layer and layer of operation onto the mind by none others but oneself. There are lots of disgusting and painful stuffs need to be exposed/released and be removed. It's like a deep cleaning process for a rubbish bin that has been accumulating layer and layer of stubborn smelly disgusting stains. It's an inevitable process. Most people don't like to go near a smelly disgusting rubbish bin, not to say, to be cleaning the bin thoroughly by themselves.
Most minds might prefer not to go near, not to say, to expose or remove any disgusting and painful stuffs that they don't want to confront with, by themselves, and want to believe that they are perfectly fine as they are, especially those who believe in a 'God existence' that is responsible for everything, and will bless them with everything good and take away anything bad, if they pray hard enough, that there's nothing that need to be removed/purified from their minds urgently by themselves, where they either think and believe that they are free from ignorance and impurities, or they are okay with the presence of ignorance and impurities, that they are not interested to be free from ignorance and impurities. And that's their freedom.
Even Siddhartha Gautama Buddha was not being exempted from had to go through great challenging purification process prior to his enlightenment.
Of course, none need to compare oneself with any others on the path of self-inquiry and self-realization. But then, once the mind has the correct understanding, it won't put the blame onto the practice and judge the effect of the practice as something 'bad', but instead, the mind will appreciate all those deep buried disgusting and painful stuffs being exposed and released to the surface of the mind, to let them go.
It's just that the path of yoga and meditation for self-inquiry and self-realization might not be suitable for the minds that have not yet developed certain degrees of dispassion and non-attachment.
Those who are strongly attaching towards the mind perception of a worldly life existence, and have strong identification towards the physical body and the thinking mind under the influence of certain passionate egoistic thinking and belief as who they are, where they think and believe that the terms such as 'the death of oneself or the death of loved ones', 'illness', 'pain', 'injury', 'old age', 'aloneness' and 'separation from the loved ones' are something bad, negative and terrible, where they expect only momentary desirable and enjoyable pleasant effects deriving from performing some leisure yoga and meditation practice, who are not mentally and emotionally stable and independent, who expect receiving miracle healing from somebody to remove all their painful suffering, who expect all their desires will come true under the blessing of somebody, who have aspiration for acquiring miracle power that can make the impossible to become possible or to change the world according to their desire, who have lots of passionate worldly/spiritual desire waiting to be fulfilled, they might not be suitable for serious yoga and meditation practice where going through stages of challenging unpleasant mind purification process (to confront with 'things' that the mind fears most) is inevitable for anyone on the path, unless they are ready to admit the ignorance and impurities in the mind and to confront with 'what they have been rejecting most'.
And hence, the importance of looking after one's mind before the mind loses the basic stability and clarity to have the essential reasoning and understanding that allows the mind to know and transcend itself.
During the purification process, not just that there are unpleasant names and forms arising and passing away, but there are also some pleasant names and forms arising and passing away, where the observer of all these names and forms observing all these pleasant and unpleasant names and forms coming and going equanimously, without attachment, without craving or aversion.
It's everyone's freedom for what they want and don't want to do with their life existence of the body and the perceptive/cognitive/assertive/subjective intellectual egoistic thinking mind.
Inquire the truth of everything.