Hmm, you can bypass Win32 and use native API. You can even rewrite some Winn32 APIs through another ones. However, there is no way for user mode application to do anything without somehow calling the kernel.
Though you don’t really need to import ntdll.dll functions, but use INT 2E (SYSCALL/SYSENTER) directly to call kernel services. Probably this is what mentioned in the quote you posted.