I joined HN few years ago, right away I felt 'these are my people'. The conversations are still pretty good for the most part but there is definitely a weird uptick of low effort borderline trolling comments.

I am not sure what the stats are for the site but I wouldn't be surprised if there was significant growth and when communities expand you start getting average content and average users which can change the experience old timers expect. I have seen these occur in many niche subreddits that grew.