@civodul Using ports should be simpler, but that RFC made it harder to forward ports to distribute tasks and to deploy port-based firewalls.

The ability to enumerate available services via the "HELP" command was not perceived as helpful for security, either.

As for anyone still using that RFC, the TCPMUX standard was officially abandoned in RFC 7805.

It may take another daring proposal with new ideas to bring about lasting and comprehensive change.