Having done some recent research on this, I have to say I was surprised to learn that some on the Left did push to get the mentally ill freed from what was basically prisons. But they didn't want them to go on the streets. They wanted smaller group type homes.
I don't see how anyone could have overlooked the role Reagan played. He did deinstitutionalize the mentally ill by releasing them without support systems. They ended up on the streets.
Do you now believe that? I can show you the history if you don't want to look it up. I remember specifically sitting on my deck in the 80s and reading about it in a Scientific American article.