I have been curious about how other people parse their way through HN. I think new accounts can't even downvote. It is common to see people ask about the downvotes even though the second last rule on the guideline [0] says not to question it.
I try to not downvote to disagree. I downvote misinformation, statements that are egressive towards a person and not the point they are making, responses that say "This.".
[0] https://news.ycombinator.com/newsguidelines.html
You need 501 karma for downvoting, that exact number is undocumented on the FAQ page.
https://github.com/minimaxir/hacker-news-undocumented/blob/m...
For anyone else that curious about undocumented stuff, here are some previous discussions with that github link.
https://news.ycombinator.com/item?id=16437973 (Feb 2018)
https://news.ycombinator.com/item?id=19212822 (Feb 2019)
https://news.ycombinator.com/item?id=20292361 (June 2019)
https://news.ycombinator.com/item?id=23439437 (June 2020)