It's fine that you do need the services provided by the app store. So of course do keep using it. But not all developers need it. Some already have an audience they gained by other means, and/or would gladly do their own marketing and distribution, and to them, the app store and its rules, especially the ones that pertain to UGC, are just an asinine barrier they have to clear every time they release an update.
What I'm trying to say that it's nice to have a choice. You know, like on macOS. There's the app store if you want it, but you're also free to DIY the distribution of your app if that's what works better for you.