I did not say that Seeger and MacColl launched it, but that they manipulated it. It was seen especially by Seeger as a means of making extreme left wing socialism popular with the younger generation.
Most of the folk performers of the fifties and sixties before the revival were seen as members of a niche minority group, and the new young folkies like Baez Dylan etc were looked upon as Messiahs for the cause, Of course, it turned out that they were not Messiahs, but very naughty boys and girls. The real strengths of traditional music to enhance life and society were subsequently diminished.