Tom,
Thinking on your point further (thanks for that).... I would have thought that, certainly in the UK anyway, any concept of the term 'folk' from outside the clubs, (if not from Miss Pringle jangling out 'Jackie Boy-Master on the school upright) would rather be drawn from the 'folk boom' era, taking in such performers as The Dubliners, The Clancys and The Spinners, rather than John Denver.
The Spinners were still producing top selling albums decades after the boom subsided.
All of these groups were producing sounds that were light years closer to the real thing than virtually everything that passes for 'folk' nowadays.
Jim Carroll