Nick filed issue #23966 to document these changes. Yes, these tags should be documented, so that installers don't have to guess (currently they are only exposed in importlib.machinery.EXTENSION_SUFFIXES. 

What you describe as a "simple idea" is just another hack, only addressing the issue on x86 platforms, not addressing this for soft-float/hard-float calling conventions, not addressing this for endianness, not addressing this for other platform ABIs. And for all these cases there are machines where you can run the variants on the same machine.  If you like to call this "a mess", fine. But this is reality.  I'm not creating this mess,  I'm describing this and exposing it to the interpreter.