> People higher up the chain are insecure because any loss of face is debilitating.

You don't do it in public. There's no face to lose in private (you're a subordinate, face is only lost among peers and superiors).

It is, however, not really a good idea to be 100% blunt out of the gate. There's a dance to it. But in public, I'm there to make my manager look good, and in private I'll tell them exactly what I think. Once they're confident I'm there to be at their back, it's never gone wrong, even in highly disfunctional orgs (I'm a consultant and get brought in to play "doctor" with hopeless projects a lot).