One of the liberating things when first developing a Web App for iOS was only having to support a single modern browser, allowing usage of advanced features which weren't crippled by having to gracefully support old IE versions. Only having to target a single platform with limited resolutions is also one of the few benefits I see with native iOS development.
Apple have always put the end Users Experience before Developers, so it's primarily focused on maintaining a fast, fluid browsing experience on iOS which is the most used browser for tablets and smart phones and IMO still continues to provide the best browsing experience on any mobile device.
So it doesn't follow the feature-mill factory pushed by other browser vendors, I still prefer iOS's performance focus, yearly upgrade cycle which thanks to iOS's fast upgrade adoption, iOS Web Developers get to enjoy adopting new features long before Android Web Developers who have to support the old browsers shipped on JellyBean.