Scott Page, professor at the University of Michigan and a self-described mathematical wonk, just used complex mathematical theories to explain why diversity equals greater efficiency and productivity (and are those not the reasons for which businesses exist??). And you do not need to be a math wonk to understand the basic ideas.
His conclusions ("levers"), from metaphor to mathematics, on why diversity is so relevant (and so important):
1. Prediction: different people have different models and patterns through which we see the world (the official term "Pile Sort"). The greater the diversity, the lower the error.
This boils down to: crowd error=average error-diversity (I promise his math was much fancier than mine, but the basic idea still holds).
2. Production: If you assume that production depends on types of workers, that each has positive but diminishing returns, and there no synergies, on average the more types of workers the more productivity you'll see.
The basic idea: if you don’t know the problem, you should at least know to be diverse.
3. Robustness: An update on Darwin's survival of the fittest--Fisher’s theorem, which says that the more variation in the current population, the higher the fitness in the next population.
The basic idea: this applies to people...and to companies.
4. Innovation: Experimental tests have shown that when a myriad of different (smart) agents with similar backgrounds are put to a task and compared to a randomly selected group of agents (not previously tested for intelligence) with diverse perspectives and heuristics, the diverse group almost always outperforms the group of the best by a substantial margin.
The basic idea: Different people, different (and better) results.