The best social safety net in the world can only protect you so much from the needs of your own children, absent some sort of young ladies illustrated primer taking over. So in that since parenting becomes more important to parents human thriving when other struggles die.
If you follow Raj Chetty's work on income mobility it appears that single parents in the neighborhood matter a lot more than single parents themselves. Since single parenthood is much more common for black families and our cities tend to be segregated, black kids tend to grow up around single parented kids which is a disadvantage. Basically having two awesome parents doesn't make up for having your entire world be not that. And having a single parent doesn't ruin an upbringing surrounded by people with two parent families. I think it's as much about shared culture as anything, the social norms get established by majority rule basically.