This is similar to the argument TV broadcasters used against cable TV and satellite, but eventually those broadcasters were able to include the alternative distribution mechanisms in their revenue models either by being paid for the use of their content or by being able to include the counts of cable and satellite viewership in their ratings reports to sponsors.

For now there is no mechanism to even count listeners to orphaned copies of the files. If we had the equivalent of an Arbitron or Nielsen for podcasts/audio, the problem would be solved, but services like those can’t usually track stats in the long tail, only in the high-volume end of the curve.

On a different note, if you’re not reading about The Long Tail, you should be. Your content is Tail kind of content, and your challenge will be “how do I let the absolutely widest audience know what I have for them”.
Your analogy of “why do I need the distributor” would seem to beg the question “will they reach/attract consumers you won’t?” Seems reasonable to me. I’d guess CNN gets more subscribers than any of our own sites do (grin). If CNN was interested in distribution, why couldn’t you a) track the users coming to your site to hear your streams and b) report not only the number of listeners but also the referring page?