> to appear as if they understand and control their shops [emphasis added]

Ideally, the manager would provide coordination and clerical support, and insulation from the rest of the bureaucracy (ie actually managing) without necessarily needing to understand or control the details. But if that's how they appear, upper management will classify them as overpaid secretaries, and gut their authority (and, on a selfish note, salaries). So it's important that they appear to understand and control their nominal subordinates, even if they're actually following sound advice of the form

> It doesn't make sense to hire smart people and tell them what to do; we hire smart people so they can tell us what to do.

(It may still be a impossible task, but it's a different task from having them actually understand and control things; even technical managers rarely accomplish that.)