Most of the music is from artists the listener likes a lot. This is right tail on a bell curve. For example 50% of songs might come from ten artists, 80% from 20 artists, and 90% from 50 artists. The other 10% might come from hundreds.
The RIAA is suing Ray Beckerman (prominent defense lawyer for those being attacked by the RIAA). Shame on them.
Give it five years and the RIAA will want everyone to be “making available” the knowledge of which content they possess so they can keep tabs on what’s hot. They’ve got their backwards pants on for years now, but within the five next years they will finally wake up.