I live in a suburban neighborhood with a couple bag ends, our neighborhood is pretty social. couple of neighborhood bbqs a year, kids all playing together every day, dinners, etc. It is quiet and not a lot of traffic with long term residents. I am not 100% on what exactly the key is for a town is, I think style matters, but Ive been in walkable neighborhoods without a good community, and non-walkable neighborhoods with one.
> bag ends
Never seen "cul de sac" in English before...
I'll say that when I was a kid, the neighborhood was still as it was originally built, no sidewalks. Didn't stop anyone from socializing, didn't stop kids from biking around.
The city added sidewalks there in the '00s or so, but when I go back there I almost never see anyone using them.
I think the trend of isolation and loneliness is not really related to infrastructure or stuff like "walkability." Those things are pretty minor obstacles.