On the one hand, I'm not even running 4K yet, and it is vanishingly unlikely that I will own a >4K display within the lifetime of my PS5, so this makes no difference to me.
On the other hand, I would like to see blatant false advertising punished every time it happens. "Nobody really cares" isn't much of an excuse when they clearly thought people cared enough to put it prominently on the box. Being able to play high-end video 10 years down the line is a legitimate selling point for a gaming console that doubles as media box.
It's not necessarily the most efficient, but it's the best guess we have. This is largely done by trial and error. There is no hard proof or surefire way to calculate optimal arrangements; this is just the best that anyone's come up with so far.
It's sort of like chess. Using computers, we can analyze moves and games at a very advanced level, but we still haven't "solved" chess, and we can't determine whether a game or move is perfect in general. There's no formula to solve it without exhaustively searching through every possible move, which would take more time than the universe has existed, even with our most powerful computers.
Perhaps someday, someone will figure out a way to prove this mathematically.