I think the difference between development for a “real” OS is that windows is still mainly owned by its customers. Similar to how MacOS is. On MacOS people can still install your applications even if you don’t pay the Apple tax to avoid their pop-up warnings. (I’m not sure if avoiding the windows warnings is also something you pay Microsoft for.)

I think a better comparison would be iOS or Chrome, where you’ll realistically have to submit yourself to their stores if you want to reach most users. Which is sort of even more locked down than YouTube as some content creators on YouTube have managed to move their audience to other platforms, though sometimes by still posting teasers or at least some content on YouTube.