Yes, permission is the key, certainly. That was the point I tried to convey in my second graph.

For some successful recording artists, every illegal download of their music is a lost sale. I don't blame them for coming after copyright infringers with both barrels. That's not the case for the vast majority of musicians, however. For most independent, relatively unknown producers, a "shared" tune (I use the term shared guardedly) is not a lost sale, inasmuch as almost no one is willing to pay a buck (or even less) for an unknown artist's work after listening to a 30-second snip of a tune. What it is is increased exposure, exposure that could one day turn viral and transform an unknown artist into a national or global phenomenon.

And just to reinforce what I'm saying, my opinion on this is not that eccentric. Mike Portnoy of Dream Theater, for example, has said he doesn't care if people copy and share DT's stuff. (Although, I must admit, they did go after sites that released bootlegs of their last album before the official release date.) And DT is not exactly small-time.