Because almost every complex system that includes facilities controlling its own complexities, has a tendency to increase the resources and structural complexity spent on that task.

If this is not actively kept in check, such a system can deteriorate over time, by a positive-feedback loop of newly created controlling facilities created to control the increasing amount of facilities.

This is not to say that managing roles are not required. Of course they are. Complex systems need control. But the proliferation of that control needs to be kept in check, otherwise, the mechanism that is initially helpful (creating structure to control complexity), will become a problem by creating additional complexity of its own.