Earlier quoted context omitted.
Isn't that the case everywhere? But the catch is that you aren't set free until you are considered cured and/or safe to set free. For many, this means never.
Unfortunate reality is some mental disease can't be effectively treated, if you can't clear the barrier of "not a danger to self or others" then it's best for society to keep a patient isolated from it. Still, our history with mental health facilities shows that we have a less than stellar reputation of actually treating individuals - wouldn't surprise me if to this day there are still people locked up in these place…
I think a problem in the US (at least by appearance) is that the regular prison system for those found same offers too little rehabilitation and care fit minor psychological disorders such as hyperactivity disorders etc. Locking half as many people up for half as long as they are currently would quadruple resources available to rehabilitate those who need it.