Doesn't Rust have enough support for operator overloading to be able to build a reasonable RangedNumber library without needing explicit language support? That seems to have been enough for C++ users over the years. I suppose it might be nice to have range checking for the builtin types available in debug builds, but I'd be very wary of putting a range constraint in code with no guarantee that it'd be enforced in any way.
Twenty years ago when I did some work in Ada for 68020s, it was general practice to put range constraints on everything that moved. I don't remember anybody ever questioning it, even in a fairly performance-sensitive environment, but I was very wet behind the ears at the time and don't know how many real bugs this caught in practice.