We live on a cul de sac and know everyone in our neighborhood. It helps that many of them are members of our church, but many of them are not. We host an annual neighborhood Advent party and get pretty good attendance. I think it makes for a much healthier neighborhood and society when people know each other, and I'm not one naturally inclined to get to know people. It is just important.
If you take the classes in the foster system you don't need all kinds of data to see how the nuclear family is in general healthier and better for children; it is obvious. But one thing they talk about is the social safety net. That is, when something goes wrong or when there is an emergency, how do things get taken care of? If you're unexpectedly detained and the first grader are coming home from school, is there a neighbor who can take him? Does the kid know the neighbor? Or is it a big ordeal? Or does the first grader just hang out by himself? That's a small example, but there are many much bigger ones. Kids in the foster system have no social safety net; when Plan A fails in their home setting, there is disaster because Plan B is either non-workable or involves people who lack any personal investment in making it work, and Plan C is non-existent. Churches, neighborhoods, and extended family (especially grandmothers) don't play a primary role according to Plan A, but they play a crucial secondary role and come off the bench pretty often, and in many cases play starting roles for most of the season.
This is what makes things like the "Life of Linda" so sick. It is the government replacing the inter-workings of social life. A federal program is not at all the same thing as a village. It takes a village to raise a child. But it takes villagers to make a village. And it takes a male and a female villager to make a tiny new villager, and it takes a marriage of that male and female to put that tiny new villager in the best position to one day be an asset to the village, meaning a source of social strength and stability for others in need.