You haven't been reading then.
The legs for support and the core for power? That's backwards.
Sit in a chair, immobilize your legs, swing a bat.
Unit then your idea is just an unproven theory.
Strap your butt in a chair, bolted to the ground....should be enough support for you to show your core power.
Take the legs out of it.
Jump in the air and swing a bat.....jump straight up.... and show us all.....
Come on.......
Leave no room for interpretation or argument. .....
Waiting........
the legs are used Bobby. There just used in the opposite direction than what you think. Your example of swinging in a chair is exactly how it works. The top half is going one way while the bottom is going the other way.
look at the top half go towards the pitcher while the bottom half goes the opposite way.
reciprocal movement creates force and direction. It’s counter rotation against itself. Like when you walk or run.
if we ‘use’ the legs as rotators. There will be no counter rotation. It would be all same side rotation. No cross body reciprocal movement.