There is diversity of race and gender, and then there is diversity of cultural values. The first kind of diversity can be a good thing, but the second kind will never work.
Diversity of race and sex (not gender) are only meaningful in this context if there is a distinctly unique racial and sex-based way of thinking that can’t come from someone outside of that particular race. So unless there is a unique ‘black’ way of thinking, for example, that only a black person can give you, it’s not so meaningful.
Get any 10 people together, even if they are of the same sex and race, and there is more likely than not no unanimity of opinion and a good diversity of ideas.