Suburbs are still like that. However each one is different. The block bbq always only happened because someone living there arranged it. Not every suburb had that person and so not every one had a block bbq. Likewise, kids play together when they are of close enough age. My daughter has lots of kids to play with, but my son just a few years older is frustrated because there is nobody to play with - it is completely chance that a bunch of 9-11 year old girls live in my area and few boys.