What will happen if all benches and horizontal places will get some anti homeless details? Homeless will magically disappear from the world?

If I'm being charitable, it's less about magically making homelessness disappear but forcing them out if unacceptable places/behaviors. Of course, very typically the same people most in favour of hostile architecture are also against giving people the help they need so maybe there's some magical thinking there after all lol.

I'm the weird one who wants tons of support and isn't against certain hostile architecture, but I get why I'm often lumped in with the magical thinking ones you alluded to.

I want nobody to have to sleep on a bench, but also nobody to be able to choose to do it either as that's not what the bench is for! Go sleep somewhere that's meant for sleeping and leave the bench for those who need to sit down.