I think the word "popular" can be tricky.   Collectors may have saved the songs for a variety of reasons, not just because of the quality of the song. Sometimes it was for historic purposes or to keep the song in context with another.

I do agree with what you said previously as well as your last post, but I do think it is important to note the distinction between "folk" and "popular". Too often people assume that just because a song is preserved in a book that it had to be a song that everyone new and loved centuries ago. That is often not the case.

The point I was trying to get out was made very well by your last sentence Don - the same will be true of the best of the current output of today's musicians.