if you could guarantee no cheaters I'm in

Well if that were working I doubt we'd have two dozen Anti-Cheat Systems. You can lock down a system as much as you want the cheaters will always find a way unless the game itself discourages it.

And then this isn't as much about privacy as it is about basic system security. I mean sure the privacy concern is there but it's less of a concern for most people. There's not much to gain from a rootkit with average Joe, after all their entire life is already on Instagram. No the far more serious part is that these Anti-Cheats are ripping country sized holes into your computers security, as can be seen beautifully by Genshin's kernel level ~~malware~~ anti-cheat being used as a convenient rootkit for a ransomware (https://www.pcgamer.com/ransomware-abuses-genshin-impacts-kernel-mode-anti-cheat-to-bypass-antivirus-protection/). If you are willing to compromise your PC's security for a tiny decrease in cheaters sure go ahead, but don't come crying when it inevitably blows up in your face and your PC becomes the victim of a hack exploiting this shit.

Once upon a time all Apps ran on Kernel level, there's a reason we don't do that anymore.