Not even just the neighbors and friends - people used to live in large family units with 10+ people per household. This meant a much broader support network if, for example, you got ill and couldn't take care of your kid for awhile.
This is just a reminder that a lot of the things we find comfortable aren't inherent; they're just a reflection of what the norms where during our formative childhood and early adult years.
The help with childcare is great as well as the extra hands for household chores. The biggest advantage (and the trigger for this) is that we get to spend time with my ailing dad in his remaining months or years (and he gets to know his grandkids). It also allows us to own fewer cars (2 cars in a household with 4 adults, versus 1 car for each adult). I do wish I had bought a house with an extra bed/bath, however. Not enough to make it worth moving at this time.
On HN it always sounds like you are only receiving, but actual deal ia you provide until you are really old or sick.