Sure you could re-invent source control, ownership models, bug tracking, change review and merge processes in a wiki. Or you can use the tools that we already have for that.
The main point is you need ownership and responsibility. Wikis by design don't have those things, and it shows in how people actually use them. Wiki dumpsters are popular exactly because they let people abdicate responsibility, which means docs are no one's responsibility, because no one likes writing docs.
