WLD,
"The point is that this style of music which is such a minority thing has a prestige out of all proportion."
You mean like Beethoven, Bach and Mozart - that's before we start on Shakespeare, Dickens, Hardy........
"I ain't never heard a horse sing a song, or else words to that effect - but does anyone know in what context he said it?"
It's apocryphal; I've heard it attributed to Broonzy
Whatever eejit it was, (who never had the bottle to put his name to it) was asked if what he did was folk music, his response was....
Jim Carroll