"I still say popularity is not the same as influence."

You are making the definition to fit your arguement I'm afraid. There is the influence that certain artists had on other artists, and there is influence that changes popular culture.

"Kingston Trio popularity peaked in the late 50s, waned in the early 60s and had no influence on popular music whatsoever once the Beatles and Rolling Stones and the rest of the British invasion hit the airwaves, ALL OF WHOM had been influenced by earlier recordings of blues and folk"

No arguement there. However, the artists that influenced the other musicians that you mention were not household words.   The point of this discussion was more focused on "albums" though.

"The so-called 'folk-scare' was the very brief bubble of loosely folk music inspired popular performers selling a lot of records in a couple of years "

Again, no one is disagreeing with that.   As I said earlier, the folk revival started decades earlier.   This "blip" brought the movement into a wider public consciousness - and it was altered by the commercial forces present.

"Folk music has always been a narrow niche market appealing to a broadminded, intelligent, mature audience."
I agree that it has been a narrow niche market, but I think you are creating a sterotype that isn't true.   While there is a significant part of the audience that is open minded, smart and getting older, there is also an audience with very set ways (picture many of the posters on Mudcat, people who do not always practice common sense, and young people who are discovering music for the first time - like children in schools. You can't create a narrow definition.

"The 'singer-songwriter' is a sorry substitute for a good 'folk stylist' in my opinion"
I thought you said the folk audience was openminded?   Why shut out a certain style of music?   

All songs were written by someone, even if they have been altered through time.   The technology that we live in will probably prevent us from losing site of modern songs, but I would bet that several hundred years from now you will have musicologists studying the singer-songwriters as "folk music".