Hm, interesting. I suppose it does prevent mass bot downvotes, but it also stops the community from pre-emptively removing posts such as this one that just stir up rage. Reddit would probably be unreadable without post downvotes.
Users can flag posts, which is kind of like a super-downvote. HN also penalizes posts that generate too many comments too fast, which it interprets as controversial.
Flagging would be an abuse of another feature. I don't think the original post is quite wrong as in illegal or harmful or off topic.
The commenter here's upvote counted, my downvote did not count.
And I won't just use any other available form of attack like falsely accusing the post of some wrongdoing just because I want to criticise something and that's the only way to do it.
I did leave a critical comment but that is a seperate issue because you can leave a positive comment and upvote. So the ability to comment nulls out.