If your network runs services you can set your channel to require being authed with nickserv to join. Sure people can make a new account if you ban them but the

If your network runs services you can set your channel to require being authed with nickserv to join. Sure people can make a new account if you ban them but they can on a web forum too. Or you can set channel so only voiced nicks can speak and de-voice a nick to moderate. Or even make an access list so only specific authed nicks can join. None of this is ideal though I agree.