>The main reason people want to pay is portability. ... With social, when people interact, the more music they share, the bigger library they build, and the bigger value Spotify becomes. The music service that is the simplest, fastest, and most social -- that's the one that will win.<p>Although mobile and social are tossed around so much they have almost become buzzwords, this is the most simple and direct explanation I have read that shows how these technologies integrate into a path for profitability.