People also probably make enemies on HN, and vote against people who they think have particularly loathsome opinions or against those who they've gotten in to particularly acrimonious arguments with.
Revenge voting, spite voting, and fan voting would be mostly mitigated by making comments anonymous (ie. by not showing usernames next to comments).
But people could still intentionally or unintentionally give themselves away by, for example, either signing their comment or by writing in a distinctive style.
In any case, I'm pretty sure HN will never switch to completely anonymous comments for everyone, so this is all purely hypothetical.
Revenge voting, spite voting, and fan voting would be mostly mitigated by making comments anonymous (ie. by not showing usernames next to comments).
But people could still intentionally or unintentionally give themselves away by, for example, either signing their comment or by writing in a distinctive style.
In any case, I'm pretty sure HN will never switch to completely anonymous comments for everyone, so this is all purely hypothetical.