True. I'd note a couple things here though. The per/hour rates are for creating the contract. Actual prices are fixed. The partner rates aren't likely to be charging every day of a project either, and are comparable to lawyer rates. They're expensive, no disagreement there.
Not great links but you get the gyst...
https://www.afr.com/politics/federal/revealed-mckinsey-partn...
https://www.quora.com/How-much-does-McKinsey-charge