Those studies are a pretty weak argument. The first link isn't about the type of diversity grandparent was talking about, but "informational diversity". The paper produces no direct correlation. The pragmatic angle is overblown.

It being the right thing to do is a much stronger argument imo. Which I agree with, but companies generally aren't interested in it, unless they can use it for marketing.

Can you tell me how much diversity juice I need to add to my team to make it perfect? Do I need to hire 1 black person for every white person? Please, provide me the ratio required to avoid marginal returns.

I would need to undergo DNA testing for each person to avoid hiring anyone that is too much of one race. Do I get better returns if I hire someone that has 25% of 4 different races?

Please elaborate on your very empirically verifiable and obviously logically cohesive argument. If you don't understand where my skepticism originates from, please turn your attention to the results of Black Economic Empowerment in South Africa (where racial quotas are enforced to ensure the blackest candidate is hired, not the best candidate).

Look at the performance of the South African sports teams that have been forced to recruit players not based on merit, but on the colour of their skin.