One thing that is amusing about the prevalence of advanced anti-cheat in Windows gaming is it's actually causing said API/ABIs to undergo ossification. A good data point is the invention of Syscall User Dispatch^1 on Linux which would allow a program to basically install a syscall handler when they originate from various regions of memory. I do not know how usable this is in practice, admittedly -- but I think the fact it was contributed at all speaks to the growing need.

^1 https://docs.kernel.org/admin-guide/syscall-user-dispatch.ht...