An MFA is an academic credential. The master-apprentice relationship is less crucial than the idea that one has spent enough time in an academic setting so as to be able to take on a job at another university, fulfill that pedagotic function. It's not about the writing, but about the teaching. It's also about publishing, to the extent that mainstream journals and book publishers want to publish the kind of thing produced in writing programs, however that kind of thing is defined at any given time.

A book publication is also an academic requirement, for tenure if not for hiring. It is an adjunct to the degree, if in the ideal flight pattern the M.A. "thesis," a book of poems, is then published by a University Press.

In order to make MFA programs really be about writing, we have to make sure they never lead to teaching jobs or book publications. Just kidding.

A smart PHD like KSM can bypass the MFA and become college professor with a book publication (or more than one) from a small press. He may have gained more cultural capital by having bypassed the Iowa MFA circuit. Of course not every poet wants to be college professor.

One caveat: I have never received an MFA or taught in an MFA program, so I am guessing about this credentialing mechanism.