Put differently: leaders are comfortable with conflict, and know how to resolve it when it arises. Silencing it doesn't resolve it.

This requires good management skills, good listening skills, and problem-solving skills.

Great leaders will make sure not only to be comfortable with conflict, but to make the their whole team knows this fact, so they come forward.

Funnily, in my experience the people that say "diversity results in better products and decision-making" (dominant view today) focus on the wrong thing, and don't realize how important conflict is, or that conflict is what leads to better decision-making. Maybe communication and leadership should be taught in schools? Certainly in universities. More great leaders probably means less need for bloated middle management too.