GP is being a little hard on the author but high framerate applies as much to apps on mobile devices as it does an FPS game on a PC, particularly if you have touch based interaction. Even just simple scrolling will feel janky if you're only hitting 60 FPS on a high refresh rate mobile device.

Have you used an iPad with ProMotion and one without? Seriously try it, you can’t tell me that there’s no perceivable difference between the two when scrolling through something or writing with a pen.