This is an old Edge essay, but still relevant. Jaron Lanier warns of hive mentality. Digital Maoism: The Hazards of the New Online Collectivism
His intro:

“The hive mind is for the most part stupid and boring. Why pay attention to it? [Wikipedia] is part of the larger pattern of the appeal of a new online collectivism that is nothing less than a resurgence of the idea that the collective is all-wise, that it is desirable to have influence concentrated in a bottleneck that can channel the collective with the most verity and force. This is different from representative democracy, or meritocracy. This idea has had dreadful consequences when thrust upon us from the extreme Right or the extreme Left in various historical periods. The fact that it’s now being re-introduced today by prominent technologists and futurists, people who in many cases I know and like, doesn’t make it any less dangerous.

Read it all.