There's no way that CPU is limiting performance to that degree in those games. It must be something else. Maybe it's simply a matter of balance. Console devs have the luxury of allocating the available bandwidth very precisely and thus adding in AF could indeed have a big impact while PC devs don't know how much bandwidth a system will have relative to it's GPU resources so they're unable to balance so carefully, thus there's often a greater surplus of bandwidth on the PC side that can be allocated to "free" AF. Obviously XBO has the esram which may help in that regard vs PS4.