This isn't a marketing thing or trying to lock other distributions out, it's about having a simple platform that people can make applications on without having

This isn't a marketing thing or trying to lock other distributions out, it's about having a simple platform that people can make applications on without having to drink from a firehose. Ubuntu-as-a-platform can make opinionated choices what to support. This is why when someone asks "How do I make an application for Ubuntu" you can answer with "Quickly and Python" instead of "well that depends." It's nice to have a default.