Earlier quoted context omitted.
It seems like people do really well for themselves after they leave McKinsey, do you think this is mostly a function of the cache having McKinsey on your resume brings? What skills are really developed as a management consultant?
Basically. It's a filter that proves someone who worked there is smart and hardworking. It also explains their virtually universal requirement for an Ivy league (or similar) background.
You don't hire overachieving 4.0 HYPS grads that have "played the game" since they were 14 because they're the smartest guys / gals around, you do it because they'll work 18 hours a day if needed. It's a great indicator of at least two things
1) The person is able to learn quick, and pick up new things very fast
2) The person has exceptional work ethics, and will do what's expected. You're driven enough to not lose motivation.
And then you set them to do menial grunt-work like fixing spreadsheets and formatting PP slides.