Also, didn't the hip hop crowd just give away their music for free and make all their money touring? Until signed anyway. And mix tapes were more than a single. So to that end, music definitely was their marketing. To put it another way, they let the music market itself. That's all they needed, and was all they got. I would put influence under marketing though, unless we can settle that music and influence are both both.
You're basically just repeating what I said, but yes. I would say influence is a little different from marketing. Marketing is you trying to reach new fans, influence is you reaching established fans.
