My wife works at in-patient psych unit in my town.
Granted, we experience nothing near the scale of problems in cities like Seattle. But even here, our city can't cope with the sheer number of folks with these mental health / substance abuse problems.
Many of my wife's patients are dangerous to themselves or to other people. They can only stay on an in-patient unit for so long. After that, the stopwatch starts ticking. How long until the next violent offense?
If there were more institutions for these people, somewhere between Hospital and Jail, at least the stopwatch would STOP more often.