Nah. Even if you disagree with the LessWrong memes on just about everything, you can easily get to 20 karma with a few moderately interesting Rationality Quotes or some such.

I've seen plenty of forums / newsgroups / collective blogs / real-life social circles that developed a powerful groupthink despite the lack of any karma-like mechanic and despite a very hands-off or nonexisting moderation.

There's far more buggy code in our brains than in our servers.