I really don't see the point since most of the music on there is actually by the bands themselves... -___-
the point is probably to protect themselves from lawsuits by content/IP owners: if there's no method in place to prevent the upload of copyrighted materials (whether or not this is a problem) then if the copyright holders find material on MySpace that they haven't licenced to be there, then MySpace can be sued for enormous amounts of money. and now they're owned by the forces of evil (aka NewsCorp) they have lots of money, and are an attractive litigation target.
however, with a 'fingerprinting' system in place, they can claim that any user who does upload copyright materials against the wishes of the copyright holder was breaching MySpace rules and ToS, meaning that MySpace wasn't at fault and
can't be sued for enormous amounts of money.