Actually Malcolm Gladwell is more than 2000 years late in writing about the optimal sie of organisations. The Romans figured this out a long time ago. For the reasons you mention, a Roman centurion was in the 150 range. So perhaps we should be reading more of Cicero than Gladwell if we want to understand modern times
another one to add to your list: "What is the definition of technology: something that doesn't work. if that's the case, what do you call something that works? A brand."