Music pirates are, like their seagoing namesakes, approaching obsolescence. Back in February, Ars Technica reported that music files account for a marginal 2.9 percent of files managed by common torrent sites. Mojo might linger on college campuses, but we’re just an isolated, compact local network, and requiring users to browse without a global search function — going through peer by peer — works with 1,800, not 18 million.