Aaron Swartz has compiled statistics that show that the bulk of Wikipedia articles are not written by the core community of editors but rather by more casual users. This makes lots of sense, when you think about it. Most people know enough to contribute substantively to Wikipedia articles on a few selected topics, and very few people know enough to contribute substantively to articles on a wide variety of topics. Furthermore, doing the research to write an encyclopedia article on a topic is a lot of work. I may be willing to work on an article about my favorite baseball player, or the college I went to, or my home town, but I probably wouldn’t do the work required to write dozens of articles.
Why does this matter? Aside from the fundamental importance of figuring out how the phenomenon that is Wikipedia has unfolded, it’s also a lesson for all of us. You may have thought, like me, that Jimbo Wales was right and that most of the core work on Wikipedia was performed by insiders. Apparently that isn’t so. If you’re a person who has hesitated to write articles for Wikipedia because you’re not an insider, get over it. It seems like most of the people contributing content aren’t.