"this seems to be (yet another) thread centred upon the alleged existence of a "priestly class of mediators"

You may or may not have noticed that a religious metaphor had been building across a number of posts, the priestly class was a response to that. I used the metonym to include all individuals who seek to create and reinforce boundaries in folk music and to divide people into categories of worthy/unworthy, saved/condemned, correct/wrong, prattish/enlightened.
Hope that helps.