I'll give you my take on this but it's just my personal take: I think you're right and wrong—right because HN does go through these waves, but wrong because it's a fluctuation process that stays fairly steady in the long run. (At least we're determined to keep it so, if we can - https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...)
That's why people have been experiencing this "HN has gotten a lot more $BAD-QUALITY recently" since pretty much the origin of the site.
I’ve been posting here for a decade, and lurking for a few years before that, and your observation tracks with my experience. There’s a handful of ideas we’re collectively mulling over at any given time. They slowly rotate in and out, and modulate into different keys as they go. For instance, the leading edge of LLM related discourse seems to be improving now that we’re getting bored with both hype and outrage, although there’s still plenty of hype and outrage. Old topics still occasionally blip into focus, but they don’t have the same staying power. Like, you’ll see a Rails post every now and then, but it’s not the darling it was. I doubt we’ll ever see the likes of “Rails is a Ghetto” make the rounds again, because nobody’s worked up about it any more. Or take Skrillex, who must have been on the front page every week for a month. I was annoyed at the time, but I think we’re due for a retrospective on programmers and dubstep. I’m not the one to write it though; not my scene in the first place.
That's why people have been experiencing this "HN has gotten a lot more $BAD-QUALITY recently" since pretty much the origin of the site.