This article makes a valid point about the hive mind, I'm just not sure that it's reddit-specific. If there were no karma on reddit, would we see markedly different behavior?

Further, there's an assumption here that everyone has an opinion on everything, which isn't the case. I think a related, and potentially more insidious problem is that the first well-crafted opinion in a thread tends to inform the opinion of followers-on, accumulating karma all the while and becoming the default position of the group.