I also went from iOS to Android (iPhone 4s -> Nexus 5x). I had my 4s for 5 years and loved it. I'd still have it if it weren't for iOS 9 being too big to instal

I also went from iOS to Android (iPhone 4s -> Nexus 5x). I had my 4s for 5 years and loved it. I'd still have it if it weren't for iOS 9 being too big to install and verizon overcharging. I've developed apps on both. Some apps have to be apps to use sensors and devices built into the phones. A lot of apps could probably get away with being mobile sites. Doubly so with some of the new html technologies being introduced by the W3C. Because Android and iPhone are owned by companies, they can move fast. The web has to accommodate for many more devices. So web standards move slower. In the time apps have become huge, a lot has been added to web standards. But I'm guessing most people haven't noticed. My guess is people are used to using frameworks and have abstracted themselves away from the basics. As a challenge to the reader, see what you can build in only JS/HTML/CSS with no server side. You'll be pleasantly surprised by what you can accomplish.