Golang's CSP idiom precludes that sharing. The language itself was explicitly designed not to preclude it: if you know what you're doing (or, unfortunately, don't), you can easily design concurrent data structures using locks or atomic operations. Golang doesn't even cordon this stuff off as "unsafe"; like in most languages, shared mutable is the default.

That said: unlike, say, string counting idioms in C, the share-using-channel idiom in Golang is powerful, in the sense of: it's what most people reach for by default.

For a language as opinionated as Golang, it's extraordinarily pragmatic. It is designed first and foremost to be a tool, and then a lot of other things, before being a statement about how to design safe programs.

I don't actually know of a single language that has locks and atomics, but marks them unsafe. All languages I know of either have them and mark them safe and idiomatic (for example, Golang or Rust), or don't have them at all (for example, Erlang).