Our team has become more and more focused on supporting two platforms with our App Development effort, Apple and Samsung. 75% of our users have an iPhone 5S or newer. The remaining 25% is a mix of Android, other iOS devices and older iPhones. Of the Android users, 80% are using some Samsung device.
Because iOS users are a significant source of potential profit.
Apple doesn't need to maximize usage in order to control the ecosystem - they just need to maximize profit potential.