Mike,
your IP metaphore does not work for me. I know why IP is there and why MACs are there.
But, frankly, I'm thinking of NNs in the same way you think of NET addresses in OSI.
An address that is independent of the topology.
And I think boot targets are special. Boot targets have to be managed before you have a complete system up,
so multipathing may not yet be ready for prime time.
But again, I should go and read and understand. It just does not make sense yet.