This is the same argument about banning on Reddit, but as a former mod, my experience is that very few people will actually go through the effort to spin up an alt to keep trolling. A handful will (we had one person who put a note in their calendar to send a “mean” modmail every month for a weirdly long time), but most are just lazy bored posters who have fun messing with people they don’t like, and if they can’t conveniently browse their targets for opportunities, they’ll just go do something else they find fun rather than go through the effort. Despite accounts being basically free and meaningless, banning trolls was unexpectedly effective.