A lot actually, since the model has all information given to it in the four views, it doesn't have to deal with any "theory of mind" of modeling the other players or being consistent over long times. See [1], there's a video of a single-player model where a car disappears behind a ball and never reappears. Multiplayer has its own risks such as the four views desynchronizing, but overall it gives a big boost to the model.

[1] https://mira-wm.com/blog-post/#hidden-information