It’s less that 4k 60fps doesn’t matter, but that most mobile cheap cameras are so poor quality that you don’t see much of a difference. The sensors are so small

It’s less that 4k 60fps doesn’t matter, but that most mobile cheap cameras are so poor quality that you don’t see much of a difference. The sensors are so small that switching to 60fps leaves less time for the shutter speed so you end up with a noisy image. On a good camera the difference is stark.