Besides, it's not just a matter of improving accuracy. Elite players are elite in multiple facets of the game. Movement, general awareness, map awareness, accuracy, etc. Many of these metrics are easy to measure.
Cheaters will show up as outliers and it is at that point that their accounts should be manually reviewed.
With casual gaming I really don't even care if someone is "cheating" to improve so long as I feel the game was fair. I can put a red dot on my screen to improve my aim, as an example.
This was impossible in Q3A (1998) without introducing an input lag thanks to client side prediction. Server also didn't send you updates on other clients that are too far away, behind a hill - you'd pretty much only receive positions of those you could see, hear or that could see you. In Warzone, you can see everyone on the map with a wallhack.
I really wonder why the game is designed this way. I guess it might be to limit required computation power of the servers? They still do stuff like hit detection, so server surely has some idea of the physics.
On top of all that, this stuff is possible even today, months or even years after such exploits being widely known. They do have a kernel-level AC driver, but they don't even seem to detect trivial hacks from the server-side.
Cheaters quit after a while because the game loses its challenge, and people being cheated leave because the game.feela unfair, and eventually there's not much of a community left.
I guess your last encounter with aimbots was in the early 00s…