Our opinions are part of this dominance/submission signaling system. The higher we feel in status the more we feel free to express distinctive opinions and expect others to agree, or at least not greatly disagree. Which is why we are so reluctant to agree with others we compete with, even when they make good points.
I eagerly admit that this is a good point. But! I don't think everybody plays this game. There is an opinion elite heterodoxy game and there is a hoi polloi orthodoxy game. In some groups, contrariness is an effective strategy of marginalization, not elevation. But this is a game I'm sure Robin and I, in our different ways, are playing. I guess that's one reason why I sort of pity people who are rigidly doctrinaire or partisan: it's so intellectually submissive. Unless, of course, you pioneered the doctrine.