Diversity is not responsible for the profitability, access to the best people for the job is. The studies cited show disparity between regions. In some regions, diversity greatly affected profitability, and in others, it did not have so great an impact.
This was largely because in regions where governments' mandated board gender quotas, either to promote gender diversity or ethnic and cultural diversity, the leadership personnel quality was diluted.
This clearly illustrates that diversity is not a critical component to delivering financial success. What delivered financial success was access to the best leadership talent, whatever the race, gender, or ethnicity. If the best leadership talent all come from the same gender or ethnicity, then so-be-it. Diversity does not foster financial success, choosing the best leaders available does.