You make out a very strong case here, Suibhne. And yes these guidelines are vague and nebulous but I can still think of a shedload of music that doesn't fit into these descriptions.

'1954: The term CAN be applied......and it CAN likewise be applied.....' I take this statement to mean 2 extremes of a whole raft of possibilities, at one end of the scale it CAN have orginated in an unsophisticated community and at the other end it CAN be composed/commercial music that has entered oral tradition. (In my OPINION the vast majority of ENGLISH folksong falls at the latter end of the scale)