We had to ban the IP block for an entire university due to troublemakers, but the problem is that one of our regulars was from the same U. One of us happened to know about such a forwarding service, so we gave him the address after a strict warning and promise that he'd behave himself.
He was having a rough time, and nobody wanted to be the one to tell him he was going to be kicked by association, so it was lucky we had a workaround.