I made a similar post a couple years ago, and it has only gotten worse - the amount of flame bait has definetly risen, the amount of attempted karma gaming+SEO has risen (eg. The K8s blog thingy), and the quality of discourse has fallen with a massive number of long standing low karma accounts proliferating.
I wonder if this might be specific to what you pay attention to. If I remember, you are Indian. I do think that there is more squabbling about Indian politics than there used to be. This isn't necessarily for the worse, but I wonder if you might be noticing and reading these posts more than others.
And while it doesn't quite answer your questions, I think HN Classic still works as a link: https://news.ycombinator.com/classic. This is the front page sorted by accounts that existed prior to Feb 2008. At a glance it looks about the same as the usual front page.
It's mostly if topics land on the front page which are controversial, then the comments will generally reflect that. Also, I have the impression that another subset of HNers tends to discuss on such topics, while others - who I associate with the more typical HN style - generally refrain from joining such a discussion, amplifying the effect.
In short, my take is to avoid controversial topic discussion forums and stick to the rest.
I'm actually surprised how well flagging works. I don't make a habit of flagging people and I flagged someone's posts that were particularly flagrant the other day and it worked rather well. I always question "is flagging a powerful tool that needs to be used sparingly?" and the experience taught me that we should probably be a little bit more liberal with flagging.
Of course flagging like all power comes with responsibility, so if flagging is used irresponsibly (for disagreement rather than quality), then that power harms the community.
If you use these things, I think it's important to ask "am I part of the September cohort?" "Am I doing this to protect values like curiosity?"
The algorithms involved in down-voting and flagging are clearly advanced enough that they can prevent some abuse.
There is a notion of "is ___ something you are, or is ___ something you do?" It can be applied to almost anything.
Is curios something I am, or is curiosity something I do? It is important to practice curiosity, not to simply "be" curious.
Please don't complain that a submission is inappropriate. If a story is spam or off-topic, flag it. Don't feed egregious comments by replying; flag them instead. If you flag, please don't also comment that you did.
Just flag spam/low-effort posts and move on with your day.
For those who think it’s not a big deal I wish to warn you that those come in numbers with the time an exhaust real people with all kind of malicious tactics including switching topics, twisting facts , personal attacks and even threats.
They never tired and take by numbers promoting designed narrative making any meaningful discussion impossible. There farms of those and I see dangerous development here because they are not stopped even though they break all the rules here.