So... it's basically kernel32.dll? That is, the shared library with a stable API across all supported platforms, and stable ABI inside any one specific platform which hides all the gritty details of switching to and back from the kernel? One wonders why it has not appeared much sooner but better late than never, I guess.
https://github.com/torvalds/linux/blob/master/Documentation/...
On Windows and other operating systems, things such as system call numbers can and do change. There's no way to interface with the kernel without linking to vendor libraries.
So on Linux you can ditch libc and write your own code. A Rust liblinux is definitely possible, I tested it. You can even have a compiler generate the system calls for you! It just needs to support the simple calling convention. No libraries necessary. I've seen a project that does just that: