Oh boy. It's NOT about whether something's "public" or not:

It's about someone "connecting the dots" between ALL your public activities.

Someone following you OUTSIDE their "space" that you visited and then invading your other spaces.

People don't usually want to mix their social circles. e.g. nobody likes a snoopy overprotective parent following their [teen] kids around wherever the children go with their friends.

Nobody likes their spouse coming uninvited on a night out with the guys/gals.

Or, when you reply to someone on HN or Reddit, and they don't like what you say about 1 specific topic, then they go and downvote ALL your comments about everything else you said!

That's perfectly legal. It's allowed. Nothing's stopping it. And hey, you commented publicly so you were "asking for it", right?

BUT IT'S A FUCKING DICK MOVE

Someone would only be able to connect the dots based on what you publicly put out there. If you don't put anything out, there's nothing to connect the dots, unless you buy some sort of dark web leaked dataset. None of your analogies are comparable to online public information because you decide what to put out online, and I never said anything about legality so not sure why you bring that up.