@threat
One of the major (and valid) points of criticism of Rust is that std relies on libc, e.g. here: https://jeang3nie.codeberg.page/rust-criticism-from-rustacean/
There is demand for a libc-less implementation — that is, I believe what Redox does.
But supporting a wide range of architectures requires tremendous effort, Redox doesn't currently support many architectures so it's easier to work with. And in any case, it's still impressive!