@lilmagi because even in the digital world, there should still be some resemblances to the real world, that's why females and males actually have genitals, bodylines and physics that similar to their real life selves(classes and races differences aside).
The primary idea that
@jorelm try to convey, if I understood right, is that having stat based upon gender is inconvenient for players to build their characters. HOWEVER, when some games have classes that locked to gender and races which is even more inconvenient for freedom of players to create chars compared to based stat, which can easily be solved with right classes abilities, items or levels.