See, I know why you "genuinely" think it's an overkill. I'll break it down to you so you know it's EXTREMELY important and having even more speed is much better to achieve semi-RAM SSD storage:
9-22GB/s means means 9-22MB/ms, so if you can stream so fast up to 22 megabytes per a millisecond that turns your storage into semi-RAM:
Old method:
PS5 method when games and engines are coded so:
This calculation was before Oodle Texture and only using lossless compression:
So now 2GB/5GB per sec/3.16 = 0.12sec, so you can stream 10GB of unique data within 0.63sec only! Which makes what Mark Cerny said 100% true, you load things as you turn in game:
Timestamped
It's far from being and overkill, and you actually would need it to be even faster if using a mouse or turning extremely fast and want to load high quality assets simultaneously to avoid having black/empty spots or pop in, it actually makes traditional RAM on PS5 going higher than 16GB might be an overkill, but that's not the case on Xbox and PC as they need to compensate with RAM (if programmed accordingly). In any case, multiplats will be designed around Xbox Series S for the next 7-6 years, which PS5 exclusives will make much more sense. On UE5 though scaling down would be easier as you can choose the frame budget for each system, but that's only for textures not AI and other calculations.