Wiki is like a game.
The important point is that playing makes only sense if you play to common rules. If someone violates the rules or starts lengthy discussions about the rules - this way disrupting the game -, he spoils the game.
Imagine some people playing street soccer. Now someone enters the game "may I join?" - "Yes, ok". After a few moves he starts a discussion about changing the rules. The normal reaction in real life will either be: "Yes, ok, why not." or "No, play to our rules or move out". In real life people accept such quick decisions as making sense. Wiki visitors often do not want to understand - for whatever reasons - that it is justified that the current players define the rules. And that it is more important to have fun playing than going into rule discussions.
Some communities deliberately have SillyRule?s as a way of weeding out AntiAuthoritarians. Eg: HTwoGTwo's "no spitting", meatball's UseRealNames "gauntlet", BookShelved:SimpleRules