The only kind of diversity that is really beneficial is diversity of opinion.
The presumed partisans of diversity do everything possible to suppress the books and ideas of Charles Murray, Jared Taylor, and Professor's J. Philippe, Richard Herrnstein, and J. Philippe Rushton.
Those who claim to value diversity try to suppress the books and ideas of those men because they know they cannot defeat their opinions in a candid debate, and they know that their opinions have political implications they fear.