Developers choosing not to develope for certain platforms is totally different from the platform banning the developers or restricting the developers. You're trying to create a false equivalence. Apple has a very restrictive appstore. Others do not have such a restrictive appstore. The kindle app for android can buy books directly from amazon. The nook app can buy books from B&N.Apple distributes ebooks. Amazon distributes ebooks. Apple distributes apps. Amazon distributes apps.
Though MS 'chose' not to sell at the Amazon App Store, they still wouldn't be able to distribute third-party games at all.
A good example would be Sony's PS Mobile store. They sell games on certain Android devices, yet you can't get those games on the Kindle Fire.
All I'm saying is, if we're saying that it's unlawful to prevent companies to distribute digital content on platforms that have closed environments, then we should penalize all of them, including Amazon and Google.
The Amazon appstore is less popular and less developers support it. So, from your example, they don't have some of the Sony mobile games thats on Android. It has nothing to do with the restrictiveness of Amazon.