Originally Rock 'n' Roll was a blend of Country music & R 'n' B
both of which were local variants of Folk music.
Ergo Rock 'n' Roll is a logical entailment of the Folk process Q.E.D.

"Preacher in the pulpit,roars with all his might,
sings GLORY HALLELUJAH puts folkies all in a fright.
Now you might think it's Satan comin' down the aisle,
but it's only BILL D,Puttin' on the style."

Tongue very much in cheek. :-)