I'm not sure I detect any Graves-Frazerian absolutism

It's there in the tone of the discussion; the certainty that folklore must carry an esoteric / symbolic / occult meaning and derive from something deeper, the understanding / appreciation requires initiation - or else the sort of mystic ephiphany you imply is awaiting the reader of such cosmic debris. I suppose it counts as SteamFilk, which one finds to a certain extent in the novels of (say) Diana Wynne Jones or Phil Rickman (I would imagine young Jane Watkins would be a huge fan of Gillman's work), though their work is less densely proscriptive (or yet contrived) in terms of its own significance, or indeed terminology. I accept that for Greer Gillman-fans such things are obviously held as strengths rather than weaknesses though.

it is not necessarily the performers fault if he is not appreciated.

One of the things I remember most about a PB gig at The Bay Hotel in Cullercoats circa 1988 was an anecdote concerning Folk and Professionalism which ended with two fresh-faced amateur female hopefuls being told to 'F*ck Off' in no uncertain terms by the organiser of a gig. Whilst he found this hilarious (no one else laughed I'm sure), a number of the audience were so deeply outraged they walked out. I must admit I failed see either the humour or significance of the tale which seemed primarily designed to upset those for whom the Heart o' Folk is the very amateurism PB was scathing of and yet had done so much to engender. One audience member was equally upset when PB berated them for not getting the upper harmonies of the Santa Fe Trail chorus. Turns out this was a rehearsed and regular feature of the song & PB regularly berated his audiences for failing to spot a harmony which was obvious only to him. A similar aura of elite erudition prevailed in one of his Folk Quizzes that took place in Durham in 1991. I only managed to get ONE question right simply because I happened to have the particular record the song was from; others, as I recall, were less fortunate.