I guess, Bert, that we want to have our cake and eat it, too.--We want several definitions of "folk" depending on our context, and we'd like to be able to distinguish between them. We want a fairly general definition to cover all of the many interests of Mudcatters, from Horton Barker to Ani DiFranco to Moondog. Then, we'd like another more restrictive definition that allows us to exclude the singer-songwriters for whom "folk" is just rock without the drumkit. Then, we'd like yet another very restrictive word that refers to poeple who learned the music from their parents in some deep dark hollow, but excludes even the revivalists like Pete Seeger, for academic discussions. In each of these contexts, "folk" has a different utility, yet we wind up with a homonym that makes it difficult for us to be precise. They're all "folk" but they're different kinds of "folk"s.
Sandy--the problem with decrying mimesis is that Frank Proffitt became Frank Proffitt by imitating the other people on Beech Mountain where he grew up. Mimicry is the way we learn. So you need to distinguish between the mimicry that allows members of a community to learn the style of their community and whatever it is you don't like that the revivalists aren't doing well.