works fine in Go.
Yes, you're not getting Rust performance (tho good part of it is their own compiler vs using all LLVM goodness) but performance is good enough and benefits for developers are great, having goroutines be so cheap means you don't even need to do anything explicitly async to get what you want
Rust chose a different design space for their async implementation though, so what works well for Go wouldn't work well for Rust. In particular, the Rust devs wanted zero-cost FFI that external code doesn't need to know about, which precludes Go-like green threads.
Rust can be used in contexts like dynamic linkers, kernels, libc, microcontrollers, dynamic libraries, and all sorts of places go has no business running. And it can use async in many of them. Go works fine for many contexts but we already have languages like go that work for those contexts. Rust is for the contexts it doesn't work well for. It's painful that it keeps being pushed to support things that would make it more difficult to support the areas it is unique in supporting.