Question Why not pivot 3DOF rig around actual 3d COG

Long time lurker here with a question that's been bugging me. I've been contemplating building a 3dof racing sim for some time and it occurs to me that if instead of pivoting about a point below the seat we sat the seat in a cradle with all 3 rotational axis through the actual COG (I imagine it would be roughly through the belly button). This would eliminate the need for the actuator or motors to be lifting the body against gravity and allow much bigger angles/simulated g forces. Not needing to lift the body, just overcome the moment of interia, would allow faster motion for a given actuator/motor torque.

Why hasn't it been done? What am I missing?

Cheers,
Vern

Is this what you are talking about...

https://www.kickstarter.com/projects/feelthree/feel-three-virtual-reality-motion-simulator

Or maybe you are referring to a joyrider, like this one? It is 2DOF, but an extension to 3DOF would also be possible.
This concept is not new, but a common alternative to the pivot-mounted rigs.

I hadn't seen that. Thank you. I guess that takes the idea on from what I was imagining but yes; the rig isn't fighting gravity as well as rotational inertia.

Thank you Markus. Yes a more compact version of that was more along the lines of what I imagined. I hadn't seen any similar. I'll keep looking. Thanks again.