There is only one reason to do what this player has done, and one reason only. To see if it was actually possible. To make you understand how asinine this really is you have to understand that perhaps one out of every twenty romps actually gets you a child, and even then you really cannot chain them. Unless you have a lot of gifts, and are an extremely good character. Basically they have dedicated a unreal amount of their life to the proposition that they can make five hundred kids.
Beyond that the children are nothing but a massive nuisance. I only have between thirty and forty, and they are like a pestilence any time you walk into a town where you have a family, or multiple families they come climbing out of the woodwork. The only way to rid yourself of the vermin is to take them to the temple of shadows, and kill them.
I can only imagine how many times he had to bang that one female to get close to thirty brats from her alone. Though I will wager somewhere close to six hundred times. I haven't gotten beyond four myself. Oh and for those confused about not rounding them all up. You can only take ten or twelve non player characters on trips with you.