I haven’t seen anyone mention the theory that Nick was possessed by a demon when he killed his own family. Why is that? Is there a reason we’re brushing this theory off? I mean, except Buckleming writing it and they are incapable of writing anything but ‘I’m so evil, durr, durr.’
By accepting Sam’s declaration that there would be no new King of Hell and by not challenging it, the demons acknowledged his authority. Sam may not be the king of Hell in name, but the hand-selected followers of the most recent contender to the throne literally would not dare to face him and fight for it.