Meditation can be a powerful technology for transformation. One of the unfortunate consequences of the secularisation of meditation and proliferation of 'mindfulness courses' (for example) as the answer for anything and everything, is a larger number of people are trying meditation without any background in the context and probably little in the way of being assessed as to their suitability for such practices.
I have continued a meditation practice for over 40 years and learned with, and from Buddhist and other monastic practitioners who were living and teaching within a framework where meditation was only one aspect of practice - and not a bolt on 'mindhack' .
In my view, meditation forms can have a very beneficial effect for some people, some of the time. This is especially so when the individual is part of a spiritual tradition where meditation is one of the practices used and where experiences can be processed with help.
Meditation is not a substitute for professional medical treatment. Due diligence is required by both teacher and potential student before starting with an initial period of 'dipping your toes' in to the practice.
This would be the same if someone were to take up MMA (mixed martial arts) training. It would be reasonable to ask if the individual was in a fit state to undertake such training as that training has many benefits but which may come at a price that some are probably wiser not to want to pay.
Meditation is (in my view) best used as a tool within the specific traditions it comes from, where there is guidance and a greater overall context. Medical and mental health condition need to be taken into account for any form of more strenuous practice - as part of the purpose for such intense practice IS to bring up 'stuff' to process. Care needs to be taken that a participant can reasonably be expected to be able to encounter their thoughts and feelings with a sufficient grounding in reality.
Secular meditation also has beneficial use for many (not all) as a stress relief technique used within an overall approach to lifestyle. Once again, care needs to be taken about who engages and any red flags taken account of in the intake phase.
In summary, meditation is similar to a hot pot. It can contain very tasty and nutritious food but you also need to be able to handle the hot pot safely!