The following passage is Steve Jobs speaking, as quoted by Walter Isaacson.
(p. 568) People pay us to integrate things for them, because they don’t have the time to think about this stuff 24/7. If you have an extreme passion for producing great products, it pushes you to be integrated, to connect your hardware and your software and content management. You want to break new ground, so you have to do it yourself. If you want to allow your products to be open to other hardware or software, you have to give up some of your vision.
Isaacson, Walter. Steve Jobs. New York: Simon & Schuster, 2011.