This is why I dislike the down voting capability on sites. There's an impulse the person dislikes what they read or from how they interpreted it, and then they are able to quell that feeling with a single action vs. having to put the effort into thinking and articulating into words what they're feeling, why they are feeling it, and allow it to be publicly scrutinized - hopefully with respectful responses. This allows not only scrutiny and discourse to occur, however it also offers an opportunity for OP to potentially learn something - whether that their language wasn't articulated clearly enough and so interpreted how they didn't expect or other.
People knee-jerk upvote just as much as they knee-jerk downvote and eliminating one half of the knee-jerks has nasty side effects.
Some people say it gets unlocked after 500 karma, others say they can do it before then which makes me think a mod can activate it for an account.
It was ironic and surprising to see all these high karma accounts discuss a theoretical forum where users can’t downvote without discussing HN’s existing rules.
Frequently downvoted reasons could be added to a blacklist that requires additional elucidation before being able to submit the downvote.
This has been an interesting thought experiment. I'd expect the results might besimilar to Robot9000:
Don't remember how well it worked.
That HN hides the votes of each post is useful because you only wind-up with a vague guess as to how other posts are received.
I suspect that not offering down votes would not make people more likely to comment. I will vote and then comment to reinforce my vote.