If a comment is useful I don't really care if it was written by a human or not unless the speaker somehow matters more than the content.

Now define useful, specifically in the context of a comment on hackernews.

An LLM summarizing the contents of a blog post might be useful to you, but is a comment here the right place for something you could geneate on your own?

I would guess for most people here, real insight or opinions from others is the "useful" aspect of reading hackernews comments.

Using LLMs to generate or refine comments only moves things further away from that goal (in my opinion).