Mr Grimmelmann suspects that labels were willing to agree to Apple's terms and accept a stream of money for two reasons.

When oil prices are low, it makes sense to have a hand in the refining and retail businesses, since both provide a steady stream of money that can fund searching for new Wells and drilling.

"The point of the web is that it is open, and anyone can create a new resource, instantly get feedback, and rapidly have a money stream flowing," he says.