Do you think those that are too mentally ill, violent, or antisocial deserve to keep being displaced because they can't function in current society?
Most of them, no. Probably one percent of one percent though can not be rehabilitated so displacement is about as good as you can do unless we bring forced asylums back.
I do understand the desire to keep folks from sleeping on benches, making things smelly.
You're doing the thing I was referring to by using one end of the spectrum to judge the actions of people dealing with the other end. The ones who are just "smelly aren't the reason benches get removed. It's the ones who verbally/physically/sexually assault people, leave used needles/human waste/blood, that sort of thing. The very tiny minority of homeless people who give all the others a bad rep and ruin things for everyone. It's not the business or train station or park's or wider public's responsibility to deal with that 0.1% as it essentially takes professionals, so displacement can't be looked down on as what else are they supposed to do?