Given how the primary role of these consultants is to ultimately agree with the management's point of view, using an agreeable LLM seems much more cost effective.

One of the big features of the service is responsibility dilution or arbitrage. Paying a big consulting fee makes the advice you know you're going to get more palatable to other people. And if it doesn't work it's not your fault, and if it does work your visionary for bringing them on board

Much like the bad time CEO hired into a company to do a bunch of layoffs and cut reorganizations, people hate them, and then they leave. They're paid well for their service