Everything from Iran, Iraq to European Hungaries to US bible belt states, you can pretty much directly map failure to fringe conservatism.
Economics:
China: Life in a mid- to mega-size city is already pretty good. Yes, it isn't 50K EUR per year, but 10K EUR per year is solid middle class.
India & Indonesia: Life in a mid- to mega-size city is meh-to-OK. In the next decade, urban incomes will very likely double. After, it will be close to China today.
Socially:
All three: Family structures are incredibly deep and supportive -- way deeper than most highly-advanced countries. Part of that comes from strong religious traditions from Taoism/Confucianism, Hinduism, Islam, etc. The lack of social safety net is mostly handled by wider family.
I have much less personal experience with Malaysia, Sri Lanka, Maldives, UAE, Qatar, Kuwait, and Saudi Arabia, but I guess their story is similar to the above three, but higher income.
As long as you bend the knee to all of your family's beliefs. God forbid you're gay, irreligious or different religion, date someone of another caste/religion, etc...
> It more and more seems like "traditional", conservative societies are more successful on aggregate.
Which is a much broader claim than just stating that traditional values increase fertility rate.
After being pressed to provide examples by multiple commenters, and failing to produce even one, you can't just sarcastically pretend that we were talking only about fertility rate all along.