Using TBP download stat's as a source that people don't want to download non mainstream artists music isn't valid. People download music from TPB because they 1. Don't have access to it in their region, or 2. don't want to pay for it, but they knew what they were looking for ahead of time.
On the other hand with Indie music there are much better sources to distribute music in a p2p setting, such as Jamendo. It's better organized for Creative Commons music searches then TBP, hosts its own tracker, and offers direct downloads for content, in case the seeder ratio is low. Artists can classify their music based on style.
TBP and self promotion have nothing to do with each other. Youtube, and Jamendo are about promotion, TPB is about distributing in mass quantities. Once your indie gets huge overnight and you can't keep up with the requests for downloads, then you put your torrent on TPB, and they'll get it out there for you, but until then, promote.