The hosts are so cheap they wont do a raycast from a player to an object to see if its in line of sight, they are not going to try and scan your input looking for randomness.
You're downplaying how genuinely hard it is to do server side stuff on a game with 60+ players, a lot of this stuff is O(n^2), and the bottle necks is network packet sizes as well where players will start to complain about packet loss because they play on WiFi connection with someone else who watches YouTube or Netflix.
Apex legends does in fact do fully simulated bullet dropoff server side with temporal rewinding, and it doesn't stop hackers from just shooting you with 99% accuracy.
Its not _hard_ its $$$ expensive. You'll need bigger processors and more servers. I mean, I guess its _hard_ to choose what compromises to make, but not technically hard. Anyhow, I'm no expert.
The solution to competitive gaming is streaming, not anti-cheat. Everybody gets the same resolution, same frame-rate, same latency. Fair is fair.
Honestly think it's game consoles with keyboards and mice that are bound to proprietary crypto protocols, much like the anti-piracy that the current xbox has. Can't do video stream HID interception unless you make a robot, and you've just raised the barrier of entry so high to get rid of %99.9 of it. And in pro matches you can just watch them in person.
The point of crypto locked controllers made by and for the manufacturer's console is that tampering will cause the device to refuse to run. Which leaves you at a robot to physically manipulate the device as I said. Since it doesn't have to be an standard like HDCP, this can be locked down pretty well like the xbox one is. [0]
At that point the barrier to entry would be so annoying that online cheating will be reduced significantly, and pro tournaments will be done in person to let you prevent usage of robots. Also everyone will be using the same equipment probably provided by tournament organizers.
