Most criticisms I see of management consulting seem to come from the perspective, which I get the sense you subscribe to, that management strategy is broadly fake so there's no underlying thing for the consultants to do better or worse on. I don't think that's right, but I'm never sure how to bridge the gap. It'd be like someone telling me that software architecture is fake and only code is real.
That said, how would we measure if our KPMG engagement worked or not? There's no control group company, so any comparison will have to be statistical or vibes-based. If there is a large enough sample size this can work: I'm sure there is somebody out there that can prove management consulting works for dentist practices in mid-size US cities or whatever, though any well-connected group that discovers this information can probably make more money by just doing a rollup of them. This actually seems to be happening in many industries of this kind. Why consult on how to be a more profitable auto repair business when you can do a leveraged buyout of 30 of them, make them all more profitabl, and pocket that insight yourself? I can understand if you're an poorly-connected individual and short on capital, but the big consulting firms are made up entirely of well-connected people who rub elbows with rich people all day.
Fundamentally, there will never be enough data to prove that IBM engaging McKinsey on AI in 2025 will have made any difference in IBM's bottom line. There's only one IBM and only one 2025!
