There are some wikis where if you bother a guy on one wiki,he bans you and you learn your lesson,then on another wiki,they ban you and you can't go on that wiki.
Well,people shouldn't be banned for incidents on other wikis,because wikia staff always say "If you're banned on a wiki,there are plenty of other communities to go to". A ban for something on a different wiki messes up that phrase.
So say a guy likes one topic,gets banned on that wiki,so they like another topic,and they go to another wiki on that topic and then they go on chat,and they get banned for a month for "violating rules on other wikis".
This seems even more bad if that wiki does not have the rule that the user violated on another wiki.