MS probably wants to make sure that Series S doesn’t end up missing out on games or getting subpar experiences, given they promised their customers that it’s the same as an X just at a lower resolution. You can see how they want to avoid outcomes like Series S being confined to lower player counts, smaller maps, or other game-restricting features.

But they’ve painted themselves into a corner in this case. Split screen requires rendering the whole game twice, which the S isn’t powerful enough to do. It’s also probably a feature few players will actually use.

Seems like this case should be an exception to the parity requirements.