Your current presidential administration is not the norm. Most countries keep highly knowledgable/connected people from one administration to another, without changing them despite different political colors, especially diplomatic administration.

Trump did not name enough ambassadors, and everything turned out pretty well, no? That's because US ambassies work pretty well w/o any ambassador. Those are just prestigial distinctions, the workers don't really change. At least in France, there is at least 5 power: the administration is the 5th, and it should not be underestimated.