I think this is a good summary of the principle.
You need more of this ”equalizing” (thicker fluid) when the grip difference between the tires is large. When one tire breaks traction, the others still have lots of it: we want to keep pushing to go ahead and the goal is to prevent the slipping...
The setup reference says that thinner oil in the center causes the front wheels to unload more during acceleration. How is that possible? As soon as the front wheels start to slip, the driving force drops at the rear wheels. Wheelies are practically impossible.
If anything, I’d imagine thicker...