Bill D,
You said, "Loreena McKinnet and Bob Dylan and Kate Wolf do something a bit different from Jeannie Robertson, Almeda Riddle, The New Lost City Ramblers, and Uncle Dave Macon."
I'll submit that Almeda Riddle, who mostly sang unaccompanied ancient ballads, did something VERY different from the New Lost City Ramblers who mostly recreated COMMERCIAL country music from the 1920s and '30s.