And that taboo is probably rooted in evolutionary psychology, people have a genetically driven tendency to criticize those who advocate having less children? So could there be an instinctual drive behind it?
https://www.flashpack.com/solo/relationships/dont-want-kids-...
It's just that it wouldn't work because any group defecting and having more children would inherit the earth and you'd be back to square one, only now not even in control.
It's the same mistake as every other decel "solution".
It's so obvious, and so unbelievable that proponents don't think of it that one has to wonder, who pushes this? Qui bono?