I utterly reject the concept that folk musicians are rankable on some intuitive scale of worth, I also believe that, based on what I know of hime, neither would Guthrie (I cannot speak for Macoll). To suggest that you could take a universe that includes Rev Gary Davis, Blind Blake, as well as Guthrie, Macoll, et al., and somehow line them up in order of value doesn't even pass the giggle test.

As far as Macoll's focus on politics as an the essential element for folk music, I have this to say. Politics is just one critical axis of the the human potentiality, there are others, just as important and fully able to stand alone as a theme for a great body of art. The greatest artists work the entire spectrum of the human experience. Van Gogh's greatness lies in the fact that his vision and sensitivites encompassed both the social and political underpinnings of The Potatoe Eaters as well as works like The Starry Night that were purely revolutionary vision; based on completely orignal ideas about the translation of human perceptions through the medium of painting.

So in the end it depends on what Macoll really meant. If his arguement was that the worth of folk music flows from a narrow focus on politics, then he was indulging in self important nonsense. If his arguement was that folk music must keep a scope sufficiently broad to include politics thought, then he is right on the money.