That's... the question I just answered.
Rule No.X of the Unsaid Handbook says, "Upvoting comments when you reply to them, counts as traits of an honorable memer. Upvoting posts that are thought-provoking and original, counts as traits of an honorable memer. Upvoting no posts and no comments, or upvoting them to earn points, define a detached and essentially irrelevant memer."