When describing his period of exile from Apple — when John Sculley took over — Steve Jobs described one fundamental root cause of Apple's problems. That was to let profitability outweigh passion: "My passion has been to build an enduring company where people were motivated to make great products. The products, not the profits, were the motivation. Sculley flipped these priorities to where the goal was to make money. It's a subtle difference, but it ends up meaning everything."
They can do it because Apple hasn't optimized its organization to maximize profit. Instead, it has made the creation of value for customers its priority. When you do this, the fear of cannibalization or disruption of one's self just melts away. In fact, when your mission is based around creating customer value, around creating great products, cannibalization and disruption aren't "bad things" to be avoided. They're things you actually strive for — because they let you improve the outcome for your customer.