... we simply don't know enough about the nervous system to know the exact physio-chemical causes of mental illnesses....
I must say that I agree with everything you said in your post, except for your description of me personally.
I suppose that you could describe me as an idealist, since I dislike the current psychiatric profiles and like to focus on 'what could be'. There's probably no question that the changes I would like to see in the mental health profession may never happen in our lifetimes. But to suggest that I'm an absolute idealist, is going a bit too far, as a philosophical concept. I'm guessing that you would consider yourself to be a realist.
I think it would be impossible to describe a comprehensive plan that would work for everyone. Even if it were possible, compliance would be a problem for a whole host of reasons. For example, many posters on this site will tell you that without a doubt, they experienced a 'THC-induced psychotic episode'. They know that in order to stay free of future episodes, they will have to carefully monitor or even completely eliminate their ingestion of THC. That's it. It may be a simple solution, but whether they can, or will, or really need to is another story.
There is one treatment option that shows tremendous promise for treatment of a variety of mental illnesses, including "schizophrenia", "bi-polar", "PTSD","social anxiety" (all of which I consider psychologically damaging labels which are abhorrent and nearly useless). It is CBD oil - cheap, simple, effective and without noticeable side-effects. I think it's criminal that this remarkable substance isn't legalized and embraced world-wide for immediate use in mental health care facilities. I believe that the only reason it is not, is that it would do devastating damage to pharmaceutical industries.
In some cases psychosis may have been caused or exacerbated by a combination of things like a chemical neurotoxin in their environment, or a caffeine allergy, a brain injury, nicotine, alcohol abuse, malnutrition, dehydration, a virus, lack of exercise, lack of sleep, etc. In these cases it would obviously take a while to figure out what happened.
So for many people the exact cause of their psychosis is a bit of a puzzle. They may be convinced that stress was the cause of their psychotic break. Perhaps is was, indirectly. But what specifically caused it? Was is a stress-induced vitamin deficiency? Which vitamin? Research has shown that animals produce huge amounts of vitamin C as one of the biological responses to stress, and B complex vitamins are depleted also. Human beings are incapable of manufacturing vitamin C within their own bodies, unlike other animals. If the vitamin C is so necessary under stress, then what happens to normal neurological function when there is severe long term shortage? Perhaps the episode was a result of long term changes in the brain due to stress-induced cortisol damage?
(See link).
Can these changes be fixed? if so, how? We won't ever know until scientists and psychiatrists really start looking, rather than being content with masking the symptoms.
The point I am trying to make is that in every case, there is a reason for a mental illness, or more aptly a neurological malfunction. The reason may not be easy to find, but 98% of the psychiatrists that I know about, will insist on medicating most mental illnesses, and not try to find the cause. In my opinion, that's a travesty. It should be a rare occurrence that patients must resort to medication. Hopefully, one day, we will see more valid research and have better answers for even the most difficult cases. So I think, in essence, we agree.