One further thought came to me, that there is a distinction between authority and responsibility.
The captain cannot share his authority and remain in command, right? But when he asks for something, then the person asked has a responsibility to provide what is asked for.
That Crossair SAAB 340 crash was put down in part to the actions of the FO. He was held to share responsibility, in other words.
I was just thinking these two terms might be held to be interchangeable in some way, when they are not.