> 3. No one is forcing you to use the Mac App Store.

If your users are on iOS, you are absolutely forced to use the app store. You simply cannot provide push notifications or any other services they require over web. They have intentionally crippled Safari so you HAVE to dance to the tune of the review board, have to give 30% of your profits. There's no alternative. Sideloading? No. Web? Enjoy being stuck in Gmail webview with no add to home screen functionality.