Nobody is suggesting that Coq should be used, so stop bringing it up (strawman). And yes, Coq might have an even stricter and more expressive type system than Rust. But nobody is asking for a perfect type system (no true Scotsman). People are asking to be able to prevent users of your library to provide illegal values. Rust (and Haskell and Scala and Typescript and ….) lets you do this just fine whereas Golang doesn’t.
And personally I would much rather have the compiler or IDE tell me I’m doing something wrong than having to read the docs in detail to understand all the footguns.
My personal opinion is that - even though I’m very productive with Golang and I enjoy using it - Golang has a piss poor type system, even with the addition of Generics.