I was a consultant at a BCG (Boston Consulting Group) spinoff after graduating as the valedictorian from MBA (Carnegie Mellon), we were similar to McKinsey. After I left, I worked at at a typical corporate company who brought in McKinsey - i..e I saw both sides of this.

Best way to understand high end consultants is to understand that they recruit mostly from Ivy League Schools - e.g. Harvard and Stanford. (e.g. my consulting company was mostly Harvard and Standard).

So what are Ivy League People typically like? Well they are very smart in many ways - not just anybody can get in. But they're not nearly as smart as they think they are. There lies the problem. They have spent most of their lives, beating other people academically, and it's been programmed into them. They aren't smarter than other people, say in the top 33%. They are just more self centered and focus a lot on LOOKING good - it's a LOT easier LOOKING good than being good, and it's a winning formula. They are at odds with people who want to do real quality work.

So when you're a consultant, your job to to make the senior manager who hired you LOOK good. Nothing else matters. So there are 2 takes on that:

1) It's total BS, it helps a small group of individuals at the expense of the company including most of it's employees

2) It's smart. If you want to win, you need to look good and you should be able to deflect blame for failures on other people. Doing the right thing and helping the company is for losers. Let other people waste their time trying to actually make the company better. Actually these people are a threat to you.

Sadly, both of these viewpoints are valid, depending on your perspective. Of course, the consultant are generally too biased (some would argue too stupid) to even grok what is going on.