Fact: Outside of a very narrow range of competence, John is an astonishingly stupid, ignorant and ill-informed man who's pretty much too stupid to understand how stupid he actually is.
Fact: If things don't go exactly his way, John turns into a humorless rage-goblin who takes out his frustrations on his son because the alternative is getting over his damned self like someone without power.
Fact: John is insanely jealous of the very little bit of authority he's been granted and views its potential loss as a crime against nature.
come into play. It's pretty much impossible to watch John interact with anyone for very long without seeing a maniac obsessed with the dread that he's supposed to bow down and surrender his power to others when 'everyone' knows that this, that and the other thing happen and if it happens to work to his benefit, he didn't make the rules. He just enforces them. The reason is, of course, due to Foob Fact Twenty-Eight:
Fact: John hasn't had an original idea in his sixty-seven years on the planet; the contents of his brain are self-serving folk wisdom and crap he gleaned together from sugar packets.
Fact: John has never actually met any of the people in his life because he slots them into categories that serve his needs.
Since John is a narrow-minded dope who doesn't know what's going on and who the players are, it makes him the ideal goon. It makes him a terrible father by most people's terms but, well, not by Elly's.