[thaumasiotes]

> When people decry using the prison system as a cure-all, it's usually for things like [...] mental illness. [...] why punish people for things that [...] aren't their fault?

Because they're dangerous to society. Whether or not it's their fault, there are some people we can't have on the streets. If you plead insanity in a murder case, we don't want to release you, we want to imprison you in an asylum instead of a jail.