Their behavior is reprehensible. But there is one reason and on reason only that this sort of behavior continues to flourish, and that is that everyone is afraid to say NO to them. Diva behavior is nothing more than narcissistic behavior. And I learned way too late in my life that if you tell them no, they will back down.
What I resent about narcissistic people is that they force ME into the position of putting limits on THEIR behavior. They don’t seem to have any internal sense of limits. So they push and insist and walk all over people until they are told to stop. I have a short list of people in the harp world that I will never, NEVER deal with again exactly because of this kind of behavior. David, your conductor should have put a stop to this right at the beginning.