I don't know about "Johnny B. Goode" but "Memphis Tennessee" certainly turns up, either complete or in parts, in a'folk' music context. Ever heard Bob Davenport's version? Or Pete Coe's reworking of "Marrowbones"?

Personally, I consider that a lot of what we classify as 'Traditional/Folk Music' , irrespective of whether "Come all ye's" or "Big Ballads" was, at one time or another, the Top 40 of the day. And what about "The First Time Ever"? Or is a cross-over from 'folk' to 'pop' OK but not the other way round?