If you ask me, the number one reason is that Android and iOS have UI libraries that are specifically meant for mobile devices. Yes, you can design a web app for

If you ask me, the number one reason is that Android and iOS have UI libraries that are specifically meant for mobile devices. Yes, you can design a web app for a mobile phone, but there is nothing that guides you or gives you any help in that direction. For example, navigation between screens. On iOS, you have a nav bar at the top of the screen, and when you navigate to a new screen it slides over the current one, animating in a back button back to the previous screen. All apps behave this way, and when you have an iPhone you don't even notice this - it is just the way you interact with all apps. You would have to hand-build that on the web, or use some random library that probably uses CPU animations and looks and feels bad. Compare that with the corresponding iOS app code: self.navigationController?.pushViewController(vc, animated: true) Then add on top of that other platform-specific things like location detection, push notifications, or camera interaction. The web got those, but years later. The native libraries are simply built for the native use case, and it's a huge competitive advantage.