The problem there ... with our US Constitution is that one cannot have their freedoms taken away without due process ... and being locked up in a mental facility is very much as much a prison as a “prison” is. There is a VERY HIGH STANDARD per the U.S. Constitution before the government takes away freedoms and rights! We MUST maintain that and never turn into the (former) Soviet Union in which they USED “mental illness” as a convenient way to get rid of people!
Institutionalization is imprisonment. No question. But in many cases it protects the patients from the outside world as well as protecting the outside world from the patients.
Of course there needs to be a high bar. But there needs to be a compassionate solution to this issue and right now I would expect leftists to begin with mercy killing.