There's only a grain of truth to what you're saying here. The eccentric shaft does indeed spin at the indicated RPM, just as a crankshaft on a piston motor doe

There's only a grain of truth to what you're saying here. The eccentric shaft does indeed spin at the indicated RPM, just as a crankshaft on a piston motor does. It's just the rotors move at 1/3rd the eccentric shaft's rate, which is a design feature enabling substantially higher than 7000RPM with little effort.