I think there are secondary effects. While technical expertise is probably not going to be affected, team dynamics will be affected through diversity in critica

I think there are secondary effects. While technical expertise is probably not going to be affected, team dynamics will be affected through diversity in critical thinking and expression. That's not the same as race/gender/etc. Too much conformity within a team causes the team to embrace that common ground rather than embrace differences. I'm a fairly loud, direct person. I work with other loud and direct people. We added someone to our team who is a bit quieter and quite frankly thoughtful onto the team. The effect wasn't so much that (s)he changed our technical decisions, but that we as a team started to give people apace for less confrontational disagreement. It improved our individual abilities to communicate and approach a problem from multiple angles. That is why diversity in personality is important. The hypothesis is then that race/gender/etc is correlated with intellectual diversity. Anecdotal evidence yes, but something I've found valuable.