> they wouldn't ever count as distinct syscalls.

According to whom, exactly?

If a syscall morphs into several slightly variant syscalls, then there's no way these are distinct syscalls.

If a syscall is designed to counter the flaws have been observed in another syscall, then there's no way this is a distinct syscall.

If a syscall is designed to add feature to an another syscall, then there's no way this is distinct syscall.

And so on and so forth.

If you actually look at Linux kernel code, you will quickly note that a lot of these related syscall even happen to share a large amount of implementation code.

So, yeah