> I'm a little confused, as that doesn't seem to block on my machine?

Me too.

I routinely run emacs on a Raspberry Pi IV building large rust projects

Blocking has never been an issue

I bury the compilation buffer and carry on as usual

The main problem I have is too many options and possibilities

I think a better thing to do is organise all the third party packages with decent documentation

The documentation in the package ecosystem ranges from barely adequate to woeful with the emphasis on the latter