While I agree with this in practice, with the culture wars of the past few years, HN has recently received its fair share of people who downvote due to disagreement. It used to be that downvotes were generally reserved for poor quality comments and upvotes were given for substantive well-considered comments even when one disagreed. Eternal september and culture wars are a bad combination. It's no longer innocent ignorance in this eternal september.
I don't have a solution to offer here, but I increasingly sympathize with those that create throwaway accounts, especially now that intent is not longer considered when interpreting comments. People have been losing their jobs not for what they meant, but due to how their words were interpreted by someone else. The fact that HN doesn't allow one to delete their comments, makes these cultural changes increasingly concerning. Who knows which of our past comments will come back to bite us as society becomes less tolerant of ideas.