The American Civil Liberties Union had more to do with deinstitutionalization than conservatives. The state run snake pits that warehoused the mentally ill were closed forever by O'Connor v. Donaldson before the Supreme Court in 1975:

Primary Holding

If an individual is not posing a danger to self or others and is capable of living without state supervision, the state has no right to commit the individual to a facility against his or her will.

I have worked in a locked behavioral health facility. The key word is locked. Unlike jail, your stay there as a patient is open ended and there is no bail. You will have to take psychotropic medicine that will make you feel weird whether you want to or not, and you will be living in a ward full of seriously mentally ill people, who will sometimes get violent. You'll have to do some kind of therapy, no matter how tedious or a waste of time it may be. The food will probably be better than jail, but you might not be allowed to go outside.

Neither mental illness nor addiction can be cured, they can only be managed, and not surprisingly many people can't manage those afflictions, and so they end up with rags and dirt blackened skin sleeping on a piece of cardboard, begging for money to get loaded. You can't make them do anything, like to be at a certain place at a certain time and meet with certain people, you can only provide an opportunity.

You have obviously never been around heroin addiction. If it's around, a junkie is going to use. Counseling and support are not magical, and almost never work even in high dollar recovery centers where the patients are locked in, and are dealing with actual doctors. Just because a smack addict is on methadone doesn't mean they don't want some of the real deal. Addicts are horrible to be around, even serious drunks. They will steal from anyone, even their own mother, since they no longer care about people, just the high. That's why they are on the street, and that is why we will just have to get used to them, since I don't think we're going to lock them up again like before Reagan.

Thanks for your service.