[000ooo000]

If I downvote a comment, how is the author to know why? If I want to promote thoughtful discussion on HN, downvoting without explaining why does absolutely nothing to serve that goal.

[KingMob]

Not true, downvoted comments get dimmed and placed lower, so the majority of viewed comments will be higher quality.

It doesn't communicate anything to the author, true, but insulting them is still not going to get you any closer to your goal.