Sadly it's not only management consultants doing that one: there's a certain proportion of the engineering-consulting business that consists of management calling in someone with an engineering degree to give a PowerPoint presentation to validate a point or provide political cover for a decision. I don't have any experience in that myself, but more than one of my friends are in jobs like that, which pay well but don't seem to produce much job satisfaction.
As a physician, I routinely do this. I may know the answer, but the patient just sees me as a primary care guy. This is quadruply true if it is a friend or ten times true if it is a family member. Politically far more favorable for me to consult. The specialists (aka, consultants), especially in private practice, are often happy to get an occasional easy consult, and the patient/friend/family appreciates me "recruiting big guns for the problem". If I stuck to insisting I know and I'm right, then I lose credibility, no matter how much evidence I cite. It's a social/political problem, not a scientific problem. And specialists consult each other constantly. There have been days in training I wrote more consults than orders (eg: meds, tests).
