I haven't used the JVM ecosystem extensively, so perhaps I was wrong. I was under the impression that the groupId would show up in import statements in your code as well as any place where you use the fully qualified name in an expression. For example, I see some spring tutorials that contain the line import org.springframework.web.bind.annotation.RequestMapping;. Isn't org.springframework from the groupId of the package?
Fortunately, Rust doesn’t even have the rather arbitrary (and unenforced) package naming convention and I’m not suggesting that Rust should adopt it. (That design smells a bit like the stuff suggested in [Pre-RFC]: Packages as Namespaces though, which I think is a poor idea for the obvious reasons.)
Could you expand on that a bit? I'm not sure what you mean by "arbitrary (and unenforced) package naming convention". Is it a java naming thing? Also, if you have objections to packages as namespaces besides the ability to name crates of the same name in different namespaces, I would love it if you would share them over on that thread.