You live in an adversarial world. You must design systems to survive adversarial actors or the systems will collapse. It's very difficult to control people that just want to be assholes, you have to make resilient systems against assholes and that means you can't do whatever you want.
But I know you don't truly believe that the only reasonable response to "someone could murder me" is to hole yourself up in a bunker - it'd be a pretty awful way to live! You just think that everything low-trust that you do is justified, without thinking about what a world that operates by these principles would actually look like.
It would look like the internet....
No, I think about problems like this all the time, especially when it comes to regarding language and human evolution.
The internet represents a problem that humans are not developed for. We are monkeys with sizable brains and a whole lot of tribalism. I'm not generally worried about people intentionally murdering me when I'm out in the world (though unintentionally with bad driving is another story). This is because of the degree of connectivity. When I drive down the street I'm subjected to a few hundred cars. Maybe a few thousand people. All those people have a uniform set of laws that are applied to them. In general we'll have a somewhat similar view of how society will work.
This does not apply to the internet in any way at all. I am subjected to all 4 billion IPv4 addresses and a zillion jillion IPv6 addresses with people that share little in common with me. I share that same net with every criminal. With every fraudster. With every maniacal government. With people that want to steal my money. With people that want to abuse my identity. It doesn't matter how good everyone else is on the planet, I am (as are you) under attack from people that you will never be able to exact justice on.
The internet in general is a low trust world. Always has been, and unless you're in a private forum with very selected entry, always will be. Standing out and making stupid rules just makes you a bigger target for people that find them annoying. Now, they are free to make the sub private, but they won't because they want to spread their political views without any costs of having those views.