Actually, the correct analogy here is an electrical engineer who knows the the General Electric Foobar technology and can use its console to design and build an electrical system, while another engineer knows the Alacatel FizzBuzz technology and believes its superior because it can build larger systems. Neither truly understands how resistance or current actually works, because they're all abstracted away under system specific terminologies.

Manchester encoding? (assuming twisted pair ethernet, at least last time I looked into this stuff). And no, while I don't expect a developer to be able to build a NIC from first principles, I do expect someone writing a distributed application to at least know the difference between TCP and UDP. (cause that's actually HIGHLY relevant).