On my Samsung Galaxy phone, I can double-tap the Home button and it downscales the screen into the corner so I can reach the entire screen with my thumb. So there is a solution to that problem.

The main problem I have with large phones is that they won't fit into my pocket. Sure, I could get out the needle-and-thread and sew myself some larger pockets, but I shouldn't have to do that. I'd much rather just have a smaller phone.

At least Huawei and Samsung have one-handed mode that shrinks the screen.

The Huawei gesture is a sideways swipe on the navigation bar (it shrinks to the side you swipe towards).