A DE Shaw hire has a much, much higher probability of being technically inclined than a McKinsey hire. You probably are not going to find the “finance bros” you are thinking of at DE Shaw.
Sundar Pichai was a Materials Scientist at Applied Materials before he did his MBA.
He did his MS in Materials Science at Stanford.
Also, plenty of STEM background people join McK later in their careers (especially in the electronics space) because there is plenty of demand for Strategy and Management Consulting in the industrial world, as LDPs aren't as popular anymore
A surprising number of people think that MBAs have never had a job before or that STEM people don't do MBAs. They think it's like regular grad school where you can enroll straight out of college.
I am sure McKinsey has lots of technically inclined people too, but if we consider back when Bezos was working at DE Shaw (early 1990s), almost all of the (few) employees must have been highly technical (it is considered the first quant fund), while McKinsey's headcount was already 2,900 when Bezos left DE Shaw.
Today it is 2,500 people versus 45,000 people, and I would guess it is still probably true that a greater proportion of DE Shaw is technical than McKinsey.
Maybe he should have stuck with that rather than running a sprawling corporate behemoth into the ground with purely short-term, market-based, decision making and the world wouldn’t be laughing hysterically at the abomination that is Bard.