Yes, post quality is one of the factors. My point is that of course there is plenty of gaming going on and it's of the simplest form. The leaderboard only encourages this gaming mentality.
That would be an interesting experiment. However, I think it does provide a certain use, which is getting a sense of how people are perceiving the discussion. Like the audience clapping or booing during a debate.
But, then there are posts like this, which won't be read by many and probably will not reach a score of two. And, docking a karma point might discourage the longer discussion threads, which are sometimes very interesting. Overall, I don't care.