"I've never really understood the (apparently self-imposed) confusion that surrounds the term 'Folk music'."

I've said this before, Jim (probably in this thread), that it's all about people who want 'experts' to take responsibility for their choices. It works something like this:

Singer A doesn't (a) particularly like Folk Music and/or (b) know much about it, but likes some other category of music and wants to perform it in a Folk venue. He/she then conceives the notion (being a great original thinker) that "all music is folk music" and hence his/her favourite musical form can safely be played in a folk venue. Nevertheless, Singer A doesn't really have the courage of his/her convictions so demands that an Expert B validate his/her 'great thought'. When Expert B fails to do so he/she is demonised as a "Folk Policeman".