Drug addicts and the mentally ill don't have the problem of being "antisocial." They have drug addiction and mental illness. "Antisocial" is the problem that you have when you see them, and is the problem that is solved when you don't see them. It's a completely narcissistic way of looking at things.

For example, putting you in prison would also solve the problem of your objection to them. You would still be surrounded by drug addicts and the mentally ill in prison, but we wouldn't have to listen to you complain about it, so our problems would be solved.

But that's also not a good solution.