This has long been the comforting conventional wisdom, but there have been contrarians. One wrote a book-length argument:

http://www.amazon.com/dp/047173876X

The argument is more-or-less that the Saudis have in fact been struggling just to keep output more-or-less flat. Their ability to open the taps to control prices is a thing of the past. They've made massive capital investments in the field operations, yet despite very high prices and an opportunity to make staggering profits, their output has only changed modestly and has never hit the peaks they've promised in the past (12 million bbl/day, I believe was what they claimed they could do; 7-8 million bbl/day is about all they've ever done lately).