You are correct, the PS5 doesn't have VRS. It has it's own equivalent, which is handle by the Geometry Engine.
So it doesn't need those RB+. Just like it doesn't need Infinity Cache
What you don't understand, is the Geometry Engine also has control over Pixels.
Same way Cerny repurpose a CU for the Tempest Engine, he did the same for the Geometry Engine.
We’ve already seen patents for Foveated Rendering (
here is one) for the PS5 and which is used for the eye-tracking of PSVR2, and this seemingly leverages the GE of the console. It specifically mentions in the patents the varying resolution of the images based upon a users gaze.
This is more advanced than VRS Tier 2 and doing what VRS does is child's play for the Geometry Engine.
Edit:
About the 72 ROPs.
The 1080TI has 88 ROPs, so ROPs doesn't always have to be divided equally.
And 3080 TI has 112 ROPs.