Here is a very nice but longish explanation of Why Wiki Works: [1]

There's another sort of explanation on the Wikipedia page: [2]

And here's an older discussion of the same topic in relation to anonymous BBS pages: [3] to paraphrase: The drama and hatred you see on semi-anonymous forums is as bad as it gets; with total anonymity, you'll probably be better off. If you can't force people to use their real names, you should opt for a totally anonymous forum.

Wiki works under the assumption that when someone does careful, well-written work, most people are reluctant to mess it up.

pic And before someone writes, "Well what about vandals" -- yes, a very few people in our society do vantalize creative work. The above paragraph has the word "most" in it. You may want to see the DefinitionOfMost.

About Passwords

A wiki with passwords would not work any better than a wiki without, and it would require more involvement by a central administrative body. Early on in the design phase this schema was rejected because it would make the site less author-friendly.

If someone puts a password lock on a page of the wiki, claiming to be someone they're not, then how will you convince the management that this person has stolen your identity to make you look like a nasty person?

Also see TipsForContributors