I started reading HN about 2 years ago. Jokes and "Internet snark" were extremely rare, if I ever saw them at all. To me, that was the single greatest thing about HN - much more important even than the articles. Subjectively, I've noticed a gradual decline in comment quality starting about a year ago, and a much more drastic, rapid decline into a more Reddit-like culture going back only about 4-5 months.