Because of all the exercise which also causes many women athletes not to have monthly periods.
Did she win the most medals? Whomever wins the most should be the flag barer.
The decision on who carries the American Flag out on closing day is done by the votes of the athletes before the games are even over. But Biles has four golds and a silver and is widely considered the best female gymnast ever. It’s a good choice.
Besides, at least she isn’t wearing a burka.