If anything, I find the rust standard library to default to Unix too much for a generic programming language. You need to think very Unixy if you want to program Rust on Windows, unless you're directly importing the Windows crate and foregoing the Rust standard library. If you're writing COBOL style mainframe programs, things become even more forced, though I doubt the overlap between Rust programmers and mainframe programmers that don't use a Unix-like is vanishingly small.
This can also be a pain on microcontrollers sometimes, but there you're free to pretend you're on Unix if you want to.
That's the same for the C or Python standard libraries. The difference is that in C you tend to use the Win32 functions more because they're easily reached for; but Python and Rust are both just as Unixy.