(I'm not saying HN should do exactly the same thing, but one example is Slashdot's system where a comment can get downvoted in a way that tags it specifically as trolling/offtopic/whatever - https://slashdot.org/faq/mod-metamod.shtml seems to describe it alright)
I know that I have stupidly taken some downvotes personally, but later realized, those comments were maybe not bad by itself, but in that context attracting flamewar OT debates. With some extra words, I would have realized sooner.
And downvoting for merely not liking someones opinion is something I really don't like, but is explicitely allowed here.