Big consultancies such as KPMG and EY are viewed as highly credible
Ahahahaha no. You hire them to create fancy-looking slides and reports that support decisions you already made. They will include a lot of weasel words and assumptions that aren't true. Then, when shit hits the fan after management's dumb idea flopped spectacularly, management can hide behind "but we even had big consultancy corpo confirm this is a good idea" while big consultancy corpo can say "assumptions we made were not upheld due to a changing environment blah blah..." and nobody has to take any responsibility. I always call it "decision-based evidence-making".