"For 92 years, the firm has held fast to the dictum of never disclosing names of clients or the advice it gives. We were intrigued by a company that seemed to be everywhere — and nowhere at the same time."
> What makes you think the firm would allow clients to advertise its name or advice in any way?
You've got it backwards. McKinsey itself doesn't disclose their clients or their advice, but their clients are, AFAIK, under no such obligation. More to the point, it's not so much about broadcasting to the rest of the world, it's about giving cover internally within a huge enterpise that "hey, we're just following McKinsey's advice", and certainly nearly everyone internally knows that McKinsey is involved.
"For 92 years, the firm has held fast to the dictum of never disclosing names of clients or the advice it gives. We were intrigued by a company that seemed to be everywhere — and nowhere at the same time."
https://www.nytimes.com/2019/02/19/reader-center/mckinsey-he...
What makes you think the firm would allow clients to advertise its name or advice in any way?