Disagree. UN is a diplomacy tool, NATO is a defense organization. Entirely different goals, and if UN was a defense organization something else would have filled the void for diplomacy and you’d say UN wouldn’t be necessary.
You don’t play diplomacy with your friends. And you cannot get your enemies to sit down if you’re aiming a gun at them. The UN not having teeth is the point.
Ah yes, what C needs is VTABLEs.