There may be agendas to reduce reproduction, but that is different from avoiding familial life for spiritual commitment. Christian monks and priests and those of most any path have done this for millennia.

If having family, it may be more difficult for spiritual asceticism but what is not mentioned in OP is that the souls coming in have needs to do so, spiritual needs which are given access by the parents. This also may be a karmic duty of the parent, or that of love, to provide the soul a vehicle here to further its journey.

I believe when a child comes it is larger than in the choices of the parents. As time unfolds, you see the hand of the divine in all things.