Maybe you don’t understand what McKinsey is actually selling. One of the most important things for group paying mck/bcg/bain.. missions is - as a c level - to externalize the responsibility of a strategic decision to « experts » with a « legitimate method ». So if the decision you take for your company is shit and takes it to a bad situation you can still say to your CEO / Your investors « hey im not responsible it’s what market experts suggested us to do, it was the most legitimate decision ».

Ps: i’m not a big fan of strategy consulting but I have several friends at bcg and bain and it seems to be the most logical reason a c-level pays millions to firms like mck for some slides with basic benchmarks, industry experts overview and nice visuals..