I think you put entirely too much faith in our ability to diagnose mental illness and entirely too little in respecting the wishes of the individuals themselves

I think you put entirely too much faith in our ability to diagnose mental illness and entirely too little in respecting the wishes of the individuals themselves. To be able to say, "I diagnose you as sick, what you want is now invalid" is an incredibly powerful tool, and obviously open for abuse. Just a few decades ago homosexuality was considered a mental illness. Your line of reasoning would justify involuntary "treatments" for homosexuality. (And in fact, this sometimes happened.) Today, many of the homeless are likely suffering from schizophrenia. Drug-based treatments for schizophrenia have permanent, non-reversible side-effects, and lower the chance of recovery to basically zero. Today, as a non-schizophrenic person, I can tell you that if I did develop schizophrenia, I would not wish to be treated with those drugs. Would that wish suddenly become invalid because I was suffering from mental illness? To my mind, it's pretty evil to force someone to take a drug with permanent side-effects against their will.