HN may be in decline... but it's still got a VERY LONG way to go until it is as toxic as every other user-based forum on the internet. I know I was semi-late to the party, but I'm still enjoying hanging out here.
Your account's a bit older than mine, but I don't see HN as "great" anymore, not for a long time. Just "pretty sorta good", with spurts of greatness here and there. https://danluu.com/hn-comments/ was put up 3 years ago, it's still true that you can cherry pick great comments since then that probably couldn't have been made anywhere else but it seems the frequency has declined. On the other hand ignoring the threads that attract hundreds of comments can help, but now you're in a sub community that can be punctured by the larger community at any time (this is different from a community existing on a separate site). I only looked at this thread today (I thought it'd be one of those to reach >100) since I was searching to see if anyone has posted an invitation to contact for a lobsters invite recently, it's time to spend a bit of time looking for somewhere else.
Indeed, avoiding fast-rising threads or items high on the front page is necessary to find gold but there are still awesome threads. For example this one - the article itself is so-so but lots of knowledgeable people wrote good comments that are helpful if your startup is in B2B