That's a bit of a chicken-and-egg question here, too. Armies have been organized around no more than 100/150 people in a single "unit"/"team" for millennia, pri

That's a bit of a chicken-and-egg question here, too. Armies have been organized around no more than 100/150 people in a single "unit"/"team" for millennia, prior to any of Dunbar's research much less "Dunbar's Number". There were a lot of observed practical concerns that led to that number, some of which are unrelated such as top-down command structures, but some of which would be direct observations of similar (if not the exact same) phenomenon that Dunbar studied. In this case Dunbar's Number gives us far more insight into why armies have organized that way for millennia than the other way around (telling them how to organize). One group discovered it practically and Dunbar theorized about if that was just a practical local maxima or if it was a more global maximum. What becomes different in our approach post-Dunbar's Number is the added perspective of: not only has this been proven to work in millennia of military practice, but in theory we know it is a theoretical barrier in far more social situations than just those that also have confounding factors like top-down management.