I have seen ordinary (predominately mixed couples) amateur medalist comps won by f/f couples where that was permitted. Dancing is mostly about building general movement and partnering skills, and someone who gets to fully experience both sides of the task will often be at an advantage in rapidly gaining a full understanding of either role.
Some male dancers are astoundingly good at substituting or demonstrating the lady's part - not to say that there are not gender-linked components to the job, but playing either part is more about trained elements such as deep expertise, judgment, flexibility, and strength than it is about the secondary effects of sex hormones.