Johnathan Blow had an interesting view on it [1], he talks about the idea of the Cell being you somehow refactor your game to be parallelized across the SPEs. But the whole point of a game is that you're simulating a cohesive little world, and anything that is easily separable from the global view of the world is probably not core to the gameplay.

One example is sound effects, if you're generating sound effects, you can't do a good job of that without the context of the environment and what is making the noise, so you necessarily have very deep data dependencies.

[1]: (at about 22 minutes onward) https://oxide.computer/podcast/on-the-metal-9-jonathan-blow/