If all International managers are crap, then that's clearly an expectations problem and I would question the lens through which their quality is being perceived.
What is equally possible is that the critics are heavily biased (shock horror), lack perspective, and have unrealistic expectations, so they think the players are better than they are, and the manager is worse than he is.
The narrative surrounding Venables, Hoddle, Keegan, Eriksson, McClaren, Capello, Hodgson and Southgate was the same, the manager is shit and the group of players is the best it's ever been. At some point, you have to start looking at your yardstick.
Anyway, Southgate isn't a hill I'm going to die on, so this is I last I will say on it, but I defended Arteta, Emery and Wenger for very similar reasons.