I would encourage you to look at the medical costs of children in the US. My children's braces alone will cost ~$7k-10k over the life of each of them, with insurance, and to do without will cause irreparable oral damage into adulthood. Certainly, this doesn't apply to other developed or developing countries, but to say "you just need to feed them" wildly differs from reality. You're just ignoring suffering at scale by saying "it'll work itself out." It doesn't, and I can provide pages of citations, grounded in data, to support this assertion. Also, having served a short stint as a Guardian ad Litem to advocate for children going through family court, I have anecdotal observations as to failure scenarios of failures to adequately provide for children, both materially and emotionally.

Maybe the "rewarding the young" in the top comment is from the genes of savanna humans when they collected fruit, hunted and didn't care about expensive medical procedures because the latter simply didn't exist?