Management is still one of the fastest ways to a high paying job. Managers get rewarded (implicitly or explicitly) for being in charge of more people, either with better pay in the same position or by appearing to be more competitive when going for promotions. This creates a perverse incentive where someone can make decisions which promote a higher headcount at the cost of actual capability or efficiency.
It's often not even deliberate. No one sits down and says, "This language or tool kit requires a higher headcount, so I'll select it for my project". But they aren't motivated to find a more efficient approach that results in them being put in charge of a smaller team (because this would cost them and not reward them).
It's also a way to hedge risks. If you've got a single programmer working on something, they're a single point of failure and they also have huge leverage (which can be good or bad depending on the person and circumstances).
Not that middle management bloat isn't a thing...it definitely is. But I don't think it's as black-and-white as it's made out here.
