>Is it the like/upvote mechanism? Hacker News would constitute harmful social media in that case. But what might be lost is a powerful lever for democratic input in terms of content curation and moderation.

I don't think it's the upvote/downvote system itself, but the fact that you can see your own "score" that changes behaviour.

It has definitely made me more likely to comment, even when I don't have much to add, and I've noticed my comments getting more and more inflammatory/polarising over the past few months as I start to optimise for engagement.

Before I turned on noprocrast, I'd often sit there "babysitting" my comments; checking on them every 10 minutes to see how people have reacted to it.

I'd be interested to see if @dang has found similar negative effects associated with giving precise counts and scores.