In terms of merits your submission karma says very little about you, unless you submit your own articles, of course Similarly, popular comments say nothing abo

In terms of merits your submission karma says very little about you, unless you submit your own articles, of course Similarly, popular comments say nothing about you other than that people agree with you. Short comments get more upvotes. Does that make short comments necessarily more valuable than longer ones? Why have the leaderboard at all? What value does it provide, when karma says little other than activity and longevity on the part of the user?