I figured this out as an 18 yo fucking around with GMod, making gamemodes that were designed to thwart exploits and hacks.

If a professional gamedev can't figure this out, that's a skill issue, or a manager who won't listen to the devs that do not have skill issues.

Every problem you have listed has a solution in proper game architecture and optimization, and latency compensation.

There are of course no 100% perfect solutions, but there are very, very good ones. You can't stop somebody that's gonna go to all the effort to set up a seperate box that does the aimbotting and hwid spoofs itself as not being there... oh well actually you can, overtime, with serverside analysis of games and gameplay.

Literally everything you've listed is a solved problem... its just that most devs don't think these will be problems untill they're halfway through making the game, and then its too late to make low level changes without fucking up the dev cycle set by management.

Basically, the answer to most of your questions is 'yes' or 'cleverly'.

There are publically available papers on all of this.