Back in those days extremely smooth scrolling and pinch-to-zoom was something that turned mobile web browsing from annoying hurdle to a fairly pleasant experience.

Mobile hardware wasn't capable of delivering such smoothness. Apple's innovation was to prioritize UI rendering over everything else. When you're zooming, rendering stops and browser only deals with zooming. Regardless of current CPU capabilities and load, scrolling and zooming is always smooth. And turns out people care about those way more than parallel rendering.

That's some underappreciated outside of the box thinking.