I respect your awareness of that, which I'm sure is much broader than mine is. HN consumes my attention; I'm all depth and no breadth.
What I'm interested in is how well HN does at fulfilling its own mandate in its own terms. On that scale, it's getting worse—in this respect, at least, which is a big one. We're going to do something about it, the same way we've always tried to stave off the decline of this place (https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...).
I think it's both external and internal, but the internal factors are more important because a compromised immune system is more vulnerable to outer pathogens.
I'm not sure it's about HN getting larger, though. It's a bit hard to tell, but at least some of the upswing in cynical and curmudgeonly comments is coming from established users.
If you're interested, https://news.ycombinator.com/item?id=46515507 and https://news.ycombinator.com/item?id=46508115 are other places I wrote about this recently.
It's the biggest problem facing HN, in my opinion.