The obvious conclusion to me is that my standards have changed. I'm older, hopefully wiser, and less inclined to put up with bullshit. So Hacker News has improved over the years, but my expectations have gone up faster than the rate of improvement, and so it seems like the quality of discourse has gone down.
Reminds me of a comment I left on Reddit in 2012, which was basically that while it wasn't as engaging for me, it's worth remembering that there are still millions of new people who are just finding the site for the first time.
https://www.reddit.com/r/IAmA/comments/rbqwc/by_request_i_di...