I can speak only about American old time southern mountain music.

I and the people I play with consistently go back to the sources for a number of reasons including curiousity, a sense of duty, a quest for authenticity, a tendency towards purism, and looking for inspiration.

But mostly we got back because the source musicians are REALLY REALLY good. They also give you a take on the tune or song that you simply cannot get from a modern musician.

Speaking from my own experience, it can take a while before one can fully appreciate the source musicians. The more one brings to the table, the more one gets out of the listening experience.

It's a little weird but every time I listen to Maggie Hammons Parker or Ernie Carpenter or even the Carter Family I notice that they've gotten better. Amazing that they can continue to improve after death

They're not good because they're old. They're old because they're good.