It worked out pretty well for Go. Nothing else besides Erlang cracked the parallelism UX/runtime-performance code as well as Go did, and it didn't have the drawbacks of Erlang.

> rule broken by almost every language in common use

I don't think so. Go/Erlang/Java do break it (Java very recently). C/C++/Rust/C#/JavaScript/Ruby/Python/Perl/TCL don't break it. PHP ... sort of breaks it, (IMO they just hide cooperative nonparallel concurrency in a nice API, but I'm not well-informed on php)?