The problem with wiki's

Inside Wikipedia’s Inner Circle

If there’s a flaw in the Wikipedia model, it isn’t that the site relies on the wisdom of crowds too much, it’s that the site’s highest-volume contributors and editors—the people who effectively run the place—could succumb to the gravitational pull of groupthink.

The problem is that it’s difficult to engineer a way to allow for group-driven creation of content while dispersing certain responsibilities and decision-making tasks among the masses. It’s impossible to create a system that’s completely open to everyone without getting overrun by malicious vandals, so it’s hard to see how the site could avoid issuing bans or using some other form of group-imposed censorship.