Why even need PID?
Because its not direct linear control of thrust.
Delay to process inputs. Delay to spin up prop.

PID is what allows what Gretzky would say.. skate to where the puck will be..

So, it compensates. "I" compensates for wind and battery offcentre. P compensates for wobbles. D prevents constant over-corrections.

It works great until you overprop (1404 5") or have huge innertia (X class)

Well, if I'm not mistaken DJI has 5-in props on 1404 motors! Older F450 class drones had old and weak 2212 motors with 10-inch props. All of those can be considered overprop, but was flying and is still flying great, with corresponding PID tune... though not as sharp and crazy as most of today's FPV drones...

Yes. DJI Mavic/Mini are relatively big .. but very thin light prop..
But its also reason why it cant resist wind, absolutely 0 acro moves.. and cant carry GoPro or anything.