It isn't as easy as you are making it out here, it's a chicken egg problem, really. OS vendors need to provide tools to developers or else there will be no apps

It isn't as easy as you are making it out here, it's a chicken egg problem, really. OS vendors need to provide tools to developers or else there will be no apps. No apps means less users which means no customers to sell hardware/ads to. Microsoft failed to establish a healthy developer community and had to close the whole smartphone department because nobody wanted their phones. Windows Phone was a very good operating system and had very high quality hardware but because the apps were missing, people bought Android and iOS. But without the app stores and tools, developers won't get their apps to their customers.