> Browser rendering engines are pretty mature at this point, with significant GPU acceleration, and over a decade stress-testing by bloated web apps.

Even so, there is a stark difference, even more so on low-powered devices, between native apps and even the lightest of browser apps. I'm traditionally a web developer, but started developing native cross-platform applications the last 6-12 months, and the performance gap is pretty big even for simple stuff, strangely enough.