Well, part of the issue is being able to find time+energy to be part of a community. With a "work/life" balance actually being a "work/children" balance in many cases, thanks to the nuclear family, it's very difficult to find time to do anything since the expectation is that you're keeping a hawk eye on your kids at all times.

Young people (or, at least, young people who don't feel the need to work 80-hour work weeks) do actually have a significant sense of community since they still have time to be active in communities. Personally, knowing that I have people I could arrange to be around on short notice who actually care about me is an incredible boost to my mental health.