The problem is that you really don't know who Random J Commenter is. That person could be a more successful and more knowledgeable person who just happens to NOT want to be a celebrity. There are plenty of smart people who simply don't want to play the popularity game. That doesn't make their input any less valuable.

Additionally, in my opinion, you are going to find more success in following tangential ideas from someone successful. You aren't going to duplicate what pg or Joel or any of those guys have done. The real value comes from intelligent people discussing tangents to some idea or theory. And if popularity is disproportionally rewarded to the thought behind the discussion, then the result will be less contribution to the site.