Do tell??
What groundbreaking masterpiece of gaming did Halo 4 bring to the table??
The visual fidelity they were able to pack into that game. With huge sandboxes to play around in. Dynamic set pieces that the user creates/controls, Vehicles, Wildly varying weapons, customizations, diverse enemy types, maps etc. was very impressive.
If they were to remove all that stuff and place you in small corridors/arenas with no vehicles, generic weapons and no customizations, then the graphical fidelity could have been raised to uncharted like levels.
Conversely if uncharted was to be opened up to allow some of the things halo has going on, the graphical fidelity have to be lowered.