The new AP Cal 4400 features vertical clutch switching. Vertical clutch movements, as a very general rule, don't benefit as much from removal of the rotor as horizontal clutch movements. In terms of thinness too, Bulgari has this covered with the record-setting BVL 318 movement.
It really does seem like the bigger brands stick to their own visions of what a luxury chronograph movement should be, as opposed to competing with each other. The robust automatic vertical clutch movement seems to be the goldilocks approach when the brand wants to use one chronograph movement across a wide range of watch collections.