> Introducing a junior person to a large Rust system would still take a year, because it is so much more difficult than Go.

Do you really think large Golang codebases are so easy to survey? I could see the argument wrt. C++, but Rust actually has a great featureset for programming "in the large". Take a look at the k8s codebase for an example of a large project that's written in Golang - doesn't seem all that easy to get started with.