However, before the internet, pettiness and other unpleasantness had a cost. You wouldn't call up an HOA meeting, send a letter or a phone call to everyone every time you see a dude that you think is "suspicious".

The Internet and platforms like Nextdoor not only reduced that cost to near-zero but actually encourage and reward that behavior since they profit off this "engagement". Middle-class paranoid (and sometimes racist) dumbasses with too much time on their hands are the perfect target for a "growth & engagement" company; they're dumb but far from broke and thus a perfect target market for advertisers.

You may be right, but... and maybe I'm being naive here... if HN can do it, why can't local social networks? The amount of people in the network is even smaller than HN. I suppose the problem is finding good moderators that keep to an ethical standard and that ethical standard is different everywhere. Well I think I answered my own question lol