Rotating gms can prevent each individual gm from playing with their strengths due to each of them knowing they will have to hand out the game to the next one.
ex: a gm that is good at making absurd scenarios would not add absurd elements to the rotating setting because they know that the next gm that is good at ecosystem simulation would not like it and then that gm will not go too much in detail about the ecosystem because they fear it might interact with the plans of the next gm that is good at cop investigation scenarios and then in the end none of them do anything interesting by fear of messing the job of the next gm.