I was not commenting about the cash flow from producer to customer when I posted. I wanted to highlight that there are a lot of intermediates who bring no value (or little) whatsoever to the end user. Supermarkets basically charge 30% of the full price or more just to have your CD/DVD/Video Game in their shelves. Do they deserve that much of YOUR money ? They usually make more money than the artists/creators in the first place.
Of course, you can say the value of a supermarket is to bring your product's awareness to the mass market. Which is very true, because it gains a lot of visibility.
And that's exactly what something like TPB does: it gives visibility to the different creations. It's just like radio: you get to enjoy free music, with ads. Only a small minority will actually buy the CD and go to the concert, but this is still worth it. TPB a radio for files. Whether they pay the creators or not is irrelevant. It still provides "value" to the creators in the first place by spreading their creations in the Netspace.