The more I read (or Kindle) Daniel Walker Howe's What Hath God Wrought, the more antecedents I see to modern liberal reformers. For example, he describes Dorothea Dix, who is summed up well in her Wikipedia entry.
Dorothea Lynde Dix (April 4, 1802 – July 17, 1887) was an American activist on behalf of the indigent insane who, through a vigorous program of lobbying state legislatures and the United States Congress, created the first generation of American mental asylums.
Howe reports that her activism came from observing the conditions of the indigent insane in prisons, where they were often chained and beaten.
So, in the 1840's, when the Reformers took up the cause of the indigent insane, it was to put them in asylums. Over a century later, Reformers took up the cause of those in asylums, arguing against their confinement. A generation after that, Reformers took up their cause once again, now on behalf of the homeless.
I should note that some researchers have observed a large proportion of mental illness in prisons. So perhaps we have come full circle.
The mentally ill pose a really challenging problem. The libertarian approach would be for government to leave them alone as long as they are not committing crimes. Certainly, you don't permit anyone to chain them or beat them. Certainly, you admire and encourage anyone who tries to help them. But the notion that the next policy reform is going to cure the problem is, one might say, deranged.