> WinAPI access for ACLs was added in Windows 10

I'm not sure which docs you mean but that's not true. The NT kernel has used ACLs long before rust was invented. But it's indeed true that rust adds platform-specific methods based on demand. The trouble with ACLs is it means either creating a large API surface in the standard library to handle them or else presenting a simple interface but having to manage raw pointers (likely using a wrapper type but even then it can't be made totally safe).

> the de-facto standard winapi crate, which provides access to the raw syscall

Since the official Microsoft `windows-sys` crate was released many years ago, the winapi crate has been effectively unmaintained (it accepts security patches but that's it).