In terms of Forza though, the 360hz physics engine would incline me to believe that the GPU and CPU dont depend on each other (or it uses a specific core it for things it needs specifically on that frame) and the GPU essentially has all the 16.6ms available to render the frame and just grabs whatever the physics has recorded at that time from RAM.I've already explained multiple times before your post what I mean. Physics are some of the most intensive things you can calculate and process to ever exist.
It's been discussed plenty of times in the past few pages but if you want to be dismissive and flat-out call people wrong then that's your decision I guess.
EDIT:
This part in particular is hilarious though.
If that is the case, they should probably be able to squeeze more out of it. I think it's more artistic weaknesses rather than technical though where it has its downfall.