I do like this about go. And on Linux it arguably makes sense (I say arguable because DNS without CGO is still a common cause of issues and incompatibility).

But Linux has, to the best of my understanding said "yes, we are ok with users using syscalls". Linux doesn't think that glibc is the only project allowed to interface with the kernel.

But for other platforms like OpenBSD and windows they are quite simply relying on implementation details that the vendors consider to be a private and unsupported interface.

This whole thing is also separate from "is making libc the only caller of the syscalls instruction" a good and meaningful security improvement.