That's not how really how rendering works - there is no 2d or 3d, just variable complexity. On that phone, some UI activities like simple scrolling in some apps

That's not how really how rendering works - there is no 2d or 3d, just variable complexity. On that phone, some UI activities like simple scrolling in some apps might be able to fun at a full 120Hz. Many apps apps won't, and games will either dynamically render a much lower resolution to keep up (a common performance technique), or just render nowhere near 120Hz, with sub-60 being more likely. And that's at 4k. This thread is about higher resolutions. To give the same meh performance at 6k, the phone would have to be more than 2x as fast in every metric. At 8k, more than 4x as fast. All while staying within the same power envelope. That's a lot to ask for in a generational bump.