Great in theory, but there really isn't a good way to diversify if you're making apps. Yes there's Android, and some apps can make as much or more money on Android, but even if the app is making the same amount on both platforms, iOS kicking you out for no good reason could cut your income in half, which can put a company out of business almost as quickly as cutting off all of their money, if they've grown it based on what they believe to be a steady income stream.