Jim, One of the finest songwriters I have ever come across is Peter Bond. He was, and still is, a superb writer of what I consider to be folk music of the highest quality. His lyrics are acutely observant, supremely crafted, melded with astonishing tunes which are well played and well sung. You may or may not have heard of him. However according to your "rules" he would not be considered folk and that is where I think "your" systems fails ............ dramatically.