The problem is the standards and the inevitable lowering of them.
The daughter of a friend who was in the Marines for a few years complained about the lower standards imposed on female recruits. She said it would have felt better to fail honestly than to get by and pass all the tests through easier standards.
The Marine Corps is the only branch of the service that still separates men and women during basic training. The reason being is that the Corps will not lower the standards for the men just so the women can keep up.