The only other reason I can see for a powerful phone is for playing video games.

If you're just using it for communications, you don't need a flagship phone; every phone works fine for that these days. There's tons of mid-grade phones now that have excellent large screens (even OLED) and plenty of power for normal tasks (including all but the most demanding games), and quite decent cameras, without cameras protruding far out of the case like on the the top-end flagships.