Now I can see what you mean. However: physics. Momentum transfer, specifically.
A strong bull top can obviously toss around a small lightweight bottom. But it needs a lot of force from the bottom to stay stable: billiard ball hits table tennis ball.
Top and bottom of equal weights will both have to invest a lot of force in doing it. Billard ball hits billiard ball.
But short lightweight top on heavy bottom (yeah, that’s me): perfect match. He’ll feel like fucking a concrete because I’ll hardly shake when a man of 130 pounds, half my weight, will plow me. Table tennis ball hits billiard ball. On the flipping, Judo principle? Most tops know exactly where to exercise force to flip one around.
All my energy can go into posture, squeezing my ass the right moment, milking him. And as a bonus, I haven’t seen any short top who doesn’t get crazy excited when he realises he’s dominating and bullying that massive guy in front of him.