I agree that the personalities have to be all fairly extroverted for both mob and pair programming. However, as a counterpoint to it becoming hard to criticize "the collective" I've experienced that at least with pair programming the opposite trends to happen. No one had a sense of personal code ownership, so no one gets too attached to a particular implementation or feels personally criticized when criticizing code. My expectation would be that that would happen even less when mob programming. I wonder though what would happen if you had multiple mobs that never rotate team members. I could see that that might quickly escalate to a us vs them situation.