All of the pro-diversity platitudes like "diversity is a strength" are never justified with data, they're just said as truisms you're supposed to blindly believe and repeat.
Why does nobody ever talk about how homogeneity is a strength? The comradery you used to have in mining villages where all workers had a tightly shared heritage and all grew up together was probably the strongest workforce you could hope for. But workers with those kinds of strong bonds do scary things like forming unions and going on strike, we don't want any of that! And that's why Amazon tracks lack of workplace diversity as a metric for risk of union formation :)