It is a nice ideal, but I highly doubt that is the fear of Grooveshark. If that was the fear, they would have sued Myspace out of existence back in its heyday (which they probably could have, tons of pirated content was there). But they embraced it. A quick perusal of http://grooveshark.com/#/explore/popular shows that Universal Music Group artists are by far the most played, and UMG doesn't see a cent of that. I think that is the fear, a well justified one even it is trying to hold onto a dying business. Occam's Razor and all.