The problem with Wikipedia is the reaction to people trying to add crap that doesn't belong. It has been to put up barriers to adding content, making anyone who starts a new article go though more and more bureaucracy, paperwork and proving your innocence. It is the same with uploading pictures or just adding text to an article. This has led to much fewer people joining the community, and without enough editors to look after the articles, the arguments to lock down and protect only becomes stronger.

Basically Wikipedia has suffered the same fate as many mature online communities. In the beginning everyone is helping each other out and you are creating something great together. After a few years the older members of the community start getting really tired of the clueless newcomers and start complaining and setting up rules. New users no longer feel welcome and never stay long. Soon 90% are experienced members, and the newcomer perspective is lost completely. It is often not intentional, making it easier for moderators is just higher priority than letting more people participate.

I wonder if Stack Overflow will survive growing up.