In tight/smaller communities having kids younger has one massive advantage: your parents/grandparents are actually young and energetic enough to help raise them.

Having active grandparents around to pass down wisdom and share the load beats waiting until your late 30s or 40s just so you can afford to hand your kids off to expensive daycare.

Losing that family safety net is a one reason people are having fewer kids now, and I really doubt it’s making society any happier.