Has anybody noticed how "slavish imitation of sources" leads to its own breed of folk-processing? I submit that a really accurate imitation is well beyond the capabilities of just about anybody (especially myself); try comparing a recording of, say, The New Lost City Ramblers or Jeff Davis with one of their sources. The difference between the Ramblers or Jeff and, f'rinstance, Syer-Bennett or Pete Seeger is that, IMO, they've immersed themselves much more thoroughly in the musical traditions of their sources, and are trying hard not to let their more-sophisticated musical background color the music. On a more personal level, I learned much of what I learned about banjo playing from a gentleman named Rufus Crisp. So did Stu Jamison, and Woody Wachtel and (to a lesser extent) Pete Seeger. We each took from Rufus' music the aspects we liked; none of us play banjo in even a similar style.
Re taxonomy: I think it's very valuable...if there's some attempt at definition of terms. Otherwise, you wind up with interminable arguments like "Is it colder in the living room or on Thursday?" or even "Is it really folk music?"