I don't think I've ever met anyone in the business who thought they were doing what it says on the tin. This is a story you will hear over and over again: "The MD went and sold the project, but now a bunch of graduates are tasked with helping the company". I know someone who was advising a central bank, aged 22.
At best, the young consultants tell the company what they wanted to hear, and use the report as their excuse to do what they were going to do anyway.
You also have to wonder how much their public facing advice actually is based on experience, rather than being advertising. You often get these dressed-up white papers and pseudo-academic articles talking about some aspect of business coming from these firms.