I think they're doing what they have to do to avoid a mountain of spam. In my opinion that's not being selfish.
Probably because i wrote a heck of a lot of content for Wikipedia back in the early days. My link was included on some of these pages because it contained more information than Wiki on the subject. Over time links got removed and Nofollowed, it's kind of like thanks we are ranking now because of your input so go away.
Of course as a webmaster, we see wikipedia as stealing the SERPs results. It is simply ranking for a lot of keywords and is taking up an extra place in the top 10 which left only 8-9 spots for us in the top page.