This hypothesis makes good predictions in general, although I think it's a subconscious phenomenon and therefore subject to cues and priming as well as the other's actual power to retaliate.

I can't find it now, but I read a study where some form of antisocial behavior (perhaps it was keeping everything in a one-shot trustee game) became less common when the victims could see the perpetrator, even when no retaliation was in fact possible (and the perp knew it). So joining a faceless and pseudonymous community should be a perfect recipe for disregard of niceness and other cooperative instincts.

Like I said, the hypothesis makes good predictions.