Earlier quoted context omitted.
You can definitely handle some of those situations server side (the key word being "some") with enough engineering effort. In regards to player positions: check which player locations are occluded and wouldn't be visible through the geometry, then only send the valid ones for each player. Of course, doing this on high tick servers could prove to be computationally intensive. In regards to aimbots: the clients already…
>Attach some mouse movement metrics and from that you'll sometimes be able to infer the most naive aimbots instantly. see? even you do not believe that this will work
Fighting against cheating in online games is going to be a constant arms race.
That's not to say that detecting most of the naive implementations isn't worthy of the effort.
It won't always work consistently but it should be pretty obvious when someone is lerping between two quaternions. Then, you can build upon that and attempt to detect small bits of random noise that'd be applied upon said interpolation and go from there.