There was a massive conversation last week [0] about down votes (not for the first time) if you're interested. Personally I think HN largely gets moderating right in general; I don't think it's about moderating the down vote specifically, but firmly encouraging a culture of good faith debate in which the down vote plays the role of hiding bad faith/low quality content. Like GP (and anyone who uses this site at least somewhat frequently) I've seen down voted comments that seem innocuous or even thoughtful but I get the sense they're a vast exception compared to the weaponised down voting of e.g. Reddit.

[0] https://news.ycombinator.com/item?id=26810972