Because they like go, are making essentially a go extension, and so a lot of their features map directly to go features. No need to re-implement goroutines and

Because they like go, are making essentially a go extension, and so a lot of their features map directly to go features. No need to re-implement goroutines and channels etc. The type system lets them reject the programs they want to reject, but if a program is valid in the type system it can, in large part, emit essentially the same go code sans the types. I mean, I'm making some assumptions here, but that's typically the reason.