... or completely delete it! Sorry, I just don't get wikis. If somebody has an issue with information I've (or any author) posted, they email me (or any webmaster) and lets the author know about it. And then the author can change it. If you give anybody the ability to add and change information out there, how can ANYONE trust anything they read?
Wikis work best as community devices. They're not official documentation for products, so you are able to trust the information as much as you can trust info on any non-official page (fan sites, enthusiast forums etc.) The idea is that a community that's invested, will do its best to provide the best and most accurate information possible.
The other advantage is that changes happen at a much quicker pace. Lets say an update to Xion comes out that changes how skins function. Users can update the wiki with information as soon as they have it. So you have a centralized site that pulls information from a lot of different sites and developers, and quickly. It makes it easier to find information when you have one page to hit.