I can't speak for the person you replied to, but my interpretation was "diversity of minds" (or "viewpoints", etc), not gender or race.

Perhaps you'd agree that the diversity of opinions and points of view on a team is crucial, even if they're all X race Y gender.

There is a good case for holding diverse hiring practices in high esteem:

* Heterogeneity of ideas is moderately correlated to diversity of backgrounds

* Diverse teams are less prone to groupthink, more ready to acknowledge and correct for their biases, and they more readily challenge one another on a factual basis

* Hiring practices that try to offset structural biases and personal tendencies towards uniformity can access talent pools that others do not

To sum up, disregarding any political or social viewpoint, diversity is a strong value driver.

As for "intelligence", whatever that is; insofar as it can even be qualified, let alone quantified, this remains a minimal contributor to performance beyond the second sigma. Genius is contextual.

Source: me, have joined/managed high performance tech-sector teams, including extraordinary individuals from unusual/outlier backgrounds.

That’s the whole point of diversity being a blind spot, because intelligence isn’t some integer value.