What is R+B??

I have always cled r+b music as 'rhythm and blues', the stuff of proper blues musicians (Clapton, Rory Gallagher, John Lee Hooker, Muddy Waters etc etc etc). So why do all these modern pop groups like the Sugababes, TLC, Destinys Child etc. get cled as r+b? Most of them wouldn't know one end of a drumstick from the other, never mind a guitar!