"Surely you realize that Led Zeppelin "stole" blues rifs from early black jazz artists. It is not just the rap artists rhyming and stealing."
True, but they were blues, not jazz, artists. At least Page and Plant gave Willie Dixon, Robert Johnson, et al, credit for their riffs, etc. Look on any of their album notes, and you'll see credit is given to the people they "stole" from.
OTOH, I don't know of any (c)rappers who do anything other than steal (sample) from real musicians, loop it through a computer, and put their own label on what comes out the other side. The same goes for these techo re-mixer morons. Of course, I also don't listen to that BS, so I could be wrong.
If you don't have any talent or creativity (and there's not a whole lot of talent and creativity to be found in any genre of music these days), you steal/sample from those who do. That's been (c)rap's M.O. pretty much since the late 80s. I thought long ago that (c)rap was on the way out, but then again, I guess Mencken was right.
Scouts Out! Cavalry Ho!