Here's a non-contradictory summarisation:

1. McKinseys advice is for the most part useless , often their advice is just politically motivated within the clients offices 2. They have zero morals, they will advice how to optimize the gas chambers (probably not too off the mark, they probably are advising something related to uighurs somewhere, maybe how apple can hide traces of genocide fueled chips from their product lineup) if they can make a couple mills. 3. The despots/murderers recruiting them are still going to go ahead with their addiction rings/gas chambers irrespective of what McKinsey tells them. The argument isn't that McKinsey made the opioid problem worse. Maybe they did but they probably will conveniently agree with us that they were not really consequential. Still doesn't mean everyone from McKinsey shouldn't be considered a dick though.