Rising through the ranks at Andersen Consulting in the 1980s one learned the same lesson, which was translated as “After a while the normal people leave.”
Clients may be trying to hire firms with only exceptional individuals - and the top consulting firms like McKinsey contain only such people. But in terms of the INTERNAL MOTIVATION of management consultants, there is a difference between someone who is DRIVEN toward career success (i.e., firm-oriented) and someone who is PULLED toward excellent service and results (i.e., to be the best at what they do).
The difference between these individuals will ultimately show: the first will produce a larger QUANTITY of results (the objective criteria needed to rise through the ranks), the other a higher QUALITY of results (i.e., raving fans instead of merely satisfied clients).
The first is generally preferred by the consulting firm, the other consistently preferred by the client.
The first looks at short term advancement, the other at long term, more holistic success.