I assumed akvadrako downvoted that since the vote and the comment appeared very close to each other and both right after my comment. But of course, I surely could be mistaken.

And anyways, downvoting is not a big deal and they have the absolute right to do so. It's just that stating why you disagreed or downvoted would be helpful.

I don't know if it's still true, but it used to be the case that if your reply to a comment your downvote to that comment does not count. It was a pretty clever mechanism in that you could be certain any downvotes didn't come from people replying to you.

I don’t see why HN doesn’t require every down vote to have a comment. Judging from the sheets of gray on most threads, most down voted comments aren’t actually in violation of site policy, off topic, trolling, etc. It’s just a few little people disagreed. Which is fine! But it’s not constructive or interesting to just slap the commenter with your dick.

Because then every other comment would have a stream of replies justifying the downvotes - replies which, presumably, would be regular comments, and thus susceptible to further downvotes (with comments)!

In other words, this would be a huge noise generator.

With the exception that it could not have been the person you replied to. (Or yourself, for completeness)