Multiple interviews are also done because there’s far too many people in the hiring chain who don’t really need to be there. I’ve had interviews for lower-level managerial positions where literally the vice president or some other person who clearly has better things to do than to be there, is there just to “be involved”, or (in one case) all hiring decisions had to be run through the VP. I’ve done panel interviews with 6 different HR people at once who clearly just need something to justify their existence.