If you tell me, for example, that Go generics are going to be like C# generics, then I have to be familiar with the full semantics of C# generics. Essentially you tell me that in order to understand X I have to understand Y first, that's not good. Consumers of your language are not, for the MOST part, PLT nerds.
Admittedly, the Rust async/await RFC and the Go contracts proposal both discuss prior art in sections towards the end, so they are actually similar in that respect. Maybe it’s really just a question of tone and messaging, and the particular discussions that tend to end up on HN.
Visiting https://rust-lang.github.io/async-book/ I don't see any mentions of neither C# nor JS. The key difference here is the audience.
Or you could research the very detailed discussion and documentation available on the topic of C# generics.
Presumably, by the time the feature ships, the golang.org/doc entry on generics will not consist of just 'lol, they are just like C# generics, docs.microsoft.com, chum'