I’m not keen on the idea of non-WebKit web engines on iOS either because it will inevitably enable a huge contingent of lazy web developers to just display a “screw you and your device’s battery, go download Chrome” message rather than bother with crafting their sites and web apps in a web engine agnostic way. It’ll be just like when IE was the dominant browser, except this time around the dominant engine is favored by web devs and will continue to be thanks to Google’s web-centrism.