I think the prime reason we see so much of this these days is that life itself is much more complicated today than it was 50 years ago. There is no such thing as real "neighborhoods" these days. What we have is houses full of people who don't know the people who live around them because both parents are at work all day,and chances are the kids don't go to neighborhood schools.
Plus,almost nobody in those neighborhoods are FROM those neighborhoods. They all grew up in other cities,or even other states,and live there because they moved there for the work.
In addition to the above,these days everybody has all the home entertainment anyone would need. They don't have to go to high school baseball or basketball games to enjoy sports. They can sit right at home and watch games from anywhere in the nation. Sa.me with movies,theater,and any other social event you might mention
We may have more people around us than any generation in history,but we are also the most isolated generation in history.
Do I know the answers?
Nope.