My experience at Wikipedia is perfectly illustrated in the following snippet from an article by Charles Cazabon from an article titled, "Why Wikipedia Can't Work." He writes;

"The Ignorant Edit-Bully

Many people have noted this phenomenon, though I've never seen a good name for it before. In a nutshell, the problem is that a person knowledgable in a given field (but not a regular Wikipedia contributor) notices an obvious error in a page devoted to a topic in that field. They want to be a good citizen, so they edit the page and correct the error. However, within minutes, their correction has been reverted, restoring the error, and if they're particularly unlucky, they may receive a note from the person that reverts their change, accusing them of "page vandalism".

It seems that there are a large number of Wikipedia devotees or zealots who have little more to do than hang around the Wikipedia site, watching for edits to pages that they've contributed to. Any change to "their" page is taken as a personal insult and instantly reverted, regardless of its merit. What's worse is that the types of people who do this simply do not have the knowledge or intellectual tools to recognize the merit of the contribution. They would appear to typically be young people, perhaps in their first couple of years of college. They have the headstrong ignorance of the young adult, coupled with an insecurity complex that makes them unable to accept that others might have something to contribute that they themselves lack. In "real life" they would be harmless, as they wouldn't be able to stand up to others in a confrontation, but the anonymity and isolation of the internet give them the confidence to become overly assertive.

So an expert makes a contribution, sees it discarded by someone who obviously has no qualifications to judge it and all the time in the world to get their own way, and the expert simply leaves, never to contribute to Wikipedia again. The quality of many of Wikipedia's articles clearly shows this phenomenon; reading through the edit history of many pages shows it in action, graphically."