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-...
I've found there's a whole philosophy that seems to line up with my (and maybe your) perspective: https://en.wikipedia.org/wiki/Deep_ecology