Right. The whole point is that what karma really controls for is appearing useful to the community, not being useful to the community.

I agree that it has a purpose, and that we're better off with it. I don't think it's sufficient on its own, and we shouldn't fool ourselves into thinking that obsessing over it is the same as focusing on improving the community. At best, it improves only a small aspect of the community; at worst, the subgoal "think about karma and get points" takes over at the expense of all else.