> detect the supernatural aim server-side
Not possible. Sure, it might be possible to detect a player instantly snapping to the center of an opponent's head and clicking, but cheats could easily make the aim move over the course of several frames, and make the target off of the center of the head by a couple pixels to simulate someone just being really good.
I've watched some really good gamers in person. People's ability to quickly flick their mouse and pop shot to a target only 1/4" inch wide on their screen in a tiny fraction of a second is insane to me.
So being able to differentiate between a cheat that tries to behave like a god-like player (rather than simply aiming to a head in a single frame) and an actual god-like player is not possible.
> a working report system.
Also not possible because of the sheer number of reports. There are people that will report 100% of the time they lose a firefight, even if a replay makes it very obvious that the person they lost against was not cheating.
And again, even with a replay, it can be impossible to differentiate between a cheater and a really good player, except in the case of OBVIOUS cheats, like shooting through a wall with 100% accuracy, or firing into nowhere and scoring hits on targets a mile away.
At best, you could ban people from using the report system when it's obvious they're abusing it, but evaluating reports has to be a manual process, but manual processes doesn't scale when you've got a player base of 7 figures or more.