From the Phoenix article linked elsewhere:
"Swartz, however, launched a study of his own, which found a marked difference between edit-intensive users, who contribute small fixes to existing entries, and those who actually wrote the bulk of articles. "Almost every time I saw a substantive edit," he writes, "I found the user who had contributed it was not an active user of the site. They generally had made less than 50 edits (typically around 10), usually on related pages. Most never even bothered to create an account."
In other words: it's generally the core crew of several thousand dedicated Wikipedians who combine to keep the site refined and readable, correcting mistakes and counteracting vandalism. But it's usually regular folks with special expertise (the self-proclaimed Dylanologist, the amateur horticulturalist, the military buff), writing one or two or five articles apiece, who've contributed the bulk of the content. Both groups are equally important to Wikipedia's success."
http://thephoenix.com/Article.aspx?id=52864&page=2
I haven't asked GlassCobra exactly how scientific his 'study' is, but it matches my own intuition. This is precisely why I believe that our notions of the 'community' are quite incorrect in orientation, and the regular contempt and suspicion showered on IPs apparently getting uppity and on new/returning accounts is the worst possible thing for the project. I suspect that there are more people actually creating the useful content on WP than those with long-term, high-count established accounts warring on policy pages and project-space appear to imagine there are.
RR