It all depends how far back one wants to go.(or how far back their current knowledge allows them) Any discussion of Carthy should include Davey Graham..cause that's where his guitar style came from. Pete Seeger found Donnegan's music insulting..but my guess is for every 1000 teens who eased into Rock from it at least one or two became serious folkies.
I follow these things pretty closely, but it was only 4 years ago that I discovered Bosie Sturdivant (after listening to a Joe Hickerson version of "Ain't No Grave..")
Rick