Valve has a long history of standing against kernel annticheat. It is a pain to dig up old statements against it, so the best evidence of that is Valve’s own anticheat VAC avoids touching the kernel. They even recently began to require disclosure of the use of kernel level anticheat:
They recently voiced their opposition to kernel level anticheat as some thing that “ might present problematic trade-offs for the end-user in the longer term”:
Kernel anticheat is a major security issue from the perspective of the operating system, as it is a kernel level rootkit. An offline analogue would be giving a corporation the keys to your home and having them regularly come and install new cameras and microphones to see what you are doing. They might say “it is only active when you are playing a game”, but there is no technical hurdle blocking them from watching 24x7 and some of them don’t even bother to pretend it is only when playing a game. Then there is the issue of the wiring being faulty such that it occasionally sets your house on fire (search for BSOD complaints involving anticheat kernel drivers and you will find many).
As for Microsoft, I think that is a misunderstanding that came from this:
Unlike Apple and the Linux community, Microsoft does not care about end user security to take a stance against kernel anticheat. All of their security initiatives are security theater.
https://www.pcgamer.com/games/steam-now-requires-developers-...
They recently voiced their opposition to kernel level anticheat as some thing that “ might present problematic trade-offs for the end-user in the longer term”:
https://automaton-media.com/en/interviews/the-steam-deck-has...
Kernel anticheat is a major security issue from the perspective of the operating system, as it is a kernel level rootkit. An offline analogue would be giving a corporation the keys to your home and having them regularly come and install new cameras and microphones to see what you are doing. They might say “it is only active when you are playing a game”, but there is no technical hurdle blocking them from watching 24x7 and some of them don’t even bother to pretend it is only when playing a game. Then there is the issue of the wiring being faulty such that it occasionally sets your house on fire (search for BSOD complaints involving anticheat kernel drivers and you will find many).
As for Microsoft, I think that is a misunderstanding that came from this:
https://www.notebookcheck.net/Microsoft-paves-the-way-for-Li...
Here is what someone who claims to develop kernel anticheat had to say about it:
https://blog.freudenjmp.com/posts/microsoft-will-not-kill-ke...
Unlike Apple and the Linux community, Microsoft does not care about end user security to take a stance against kernel anticheat. All of their security initiatives are security theater.