In general so do I, but in this case the initial reply was a content free snipe. In that case I'm not surprised it got a downvote without investing the time in making a more complete reply.
The subsequent edit was useful, although the attitude is, well, "sharp".
As far as I've been able to tell from years of Reddit/HN, downvoting is basically a signal that says "this comment is not worth the time it'd take to rebut it--but also isn't doing anything actively harmful enough to elicit flagging."
