Folk music is very diverse. But when someone is talking about it, it all depends on which folk artist you're talking about. Although I never listened to Renaissance, just the fact that Keith Relf was in the original line-up is a plus for me. I had been a big Yardbirds fan in my teens. But Renaissance is progressive rock to me, not really folk.
When I think of folk, I tend to associate it with what I heard when I was very young. I guess this would be traditional folk. People, for instance, like Burl Ives. In high school, most of us were listening to the Beatles and the Allman Brothers. But one of my best friends was rocking out to Burl Ives. It was amusing, at least to me. Of course, I respected everything he did, even if he liked that kind of music. He was smart and kind and remains so to this day. But our taste in music was definitely not the same.
Also, of course, there is Bob Dylan who really is a folk artist. I may not like folk too much, but I think he is great. I would call what he does folk rock. I think having an 8-string or 12 string bass might have worked on some of his songs.
Personally, to me one of the most positive things about folk rock was the influence that it had on some of the Beatles' music. I think "Rubber Soul" might have turned out differently without that.
A favorite song of Ricky's, my high school friend--
