Which is sort of the point. I hate when people do this too but people started doing it because other people put them on hold. So it's basically being preempti

Which is sort of the point. I hate when people do this too but people started doing it because other people put them on hold. So it's basically being preemptively rude to someone else to keep them from being rude to you. Whether it's effective depends on who has the power in the relationship. As you say, if the President really did call I suspect he would wait (and if he didn't he'd be a fool). But when someone else calls him they're probably asking for money which means he has the power in the relationship and can hang up.