> Surely if they're just as good as she is then the opportunities open to her would also be open to the 10,000 people.
No, and to be honest I find it hard to believe anyone believes so; a lot of those positions are picked due being friends with the right people, or coming from the same universities as the people already in executive positions, and other hundreds subjective factors that have little to nothing to do with the actual capabilities needed for the role.