@Kaarme that happens if you use the concept of a western current family and society.
Take into account that they said that men were all slaves or for breeding. The breeeders are probably like stallions and there is a few of them. On the other side in any civilization with slaves they vastly outnumber the free citizens so it could be a lot less than 50% are women.
What I am thinking about is that given the rate they kill their warriors to be able to level up so much, it should reinforce the use of stallions to breed enough to kill on the arenas, and that not all the time it ends in the death of one side. Also, if the amazoness use this extreme way to level up, compared with Orario's each adventurer killing thousands of beings at the dungeon, what extreme way Rakia uses to be up to Orario's power level.
Probably the way both use is just numbers.