They may not the highest ranking members but they do have power, like when the cast of the X-men films protested Singer for writing Halle Berry poorly. And many actors are producers, like Tom Cruise. On his films he outranks directors of his own movies. They do have some responsibility, their own cast mates and crew will get the brunt of it when others don't stand up for them or look the other way because they don't want to risk a pay check. That's what the bad managers want them to do, it let's them get away with everything. When everyone is complicit nobody's going to rock the boat too hard because then people will ask questions about what they doing when x happened.