That was my initial thought too, but I think it's still a useful realization. at least one place in which this would make sense is physics response.

If your actors has a single 'update' method, the first actor would check for collisions and move before any other actors had a chance to do anything. This gives certain actors preferential treatment in movement.

Of course, you could instead plan out the dependencies better; do all collision detection before all physics response. But this is just a different way to look at 'immutability'