HN is kind of different in that downvoting as at least gated behind _something_, you cant just spin up an account and immediately downvote everything.
I don't know if r/popular is going to kill reddit but it's at least no longer interesting to me at all. It's similar to twitter in that it's mostly "outrage" with the addition of some random tiktok videos or current events like sporting sprinkled in.
You should see how much karma some people have when they finally get banned and reconsider your evaluation of that method's effectiveness. It's not difficult to grind 500 karma here, it's not a signal of anything but time spent.
Plenty of threads get flagged into oblivion because a couple of people objected to them, and several people have noticed every comment in their history getting voted down from time to time. Upranking posts by manipulation is difficult, downranking them is almost child's play.
What really offsets that isn't the karma cost for upvotes but the moderators' own manual tweaking of the knobs, sometimes correcting improper flags and changing the rankings, which can't really be gamed around.
And it doesn't change the fact I’ve posted.