"Without the framework of a uniting religion, ethnicity, or purpose, it's hard to get people to truly commit to a given community." Points out that multiculturalism is destroying our civilization. Then goes on to brainstorm completely irrelevant solutions, as if the idea of simply restoring proper homogeneity is just forbidden by a higher power.
Loneliness seems to be a common thread even in homogenous first world countries like Japan. I think the modern way of people moving all the world for economic opportunity, and the much greater emphasis on "work" probably contributes far more to loneliness than multiculturalism.
Other factors that I imagine contribute: the rise of social programs (e.g. Social Security) mean that families aren't responsible for elder care anymore.
Young people are encouraged to leave the house asap after graduating high school. Failure to do so is seen to reflect poorly on the person and their parents.
Even among middle and low income earners, sharing households is less common in the past.
The rise of extreme parenting and related reduction in parental friendships.
The housing wealth of previous generations allowing them to sell a house in Boston and relocate to Phoenix, putting grandparents thousands of miles away from their children.
The rise of both spouses working meaning the non-working spouse can't lean on the social networks of the stay at home spouse.
Widespread air conditioning leading to death of outdoor neighborhood life (e.g. sitting on the porch)
The rise of college education and the increase in going to school further from home. (As recently as the 1970s over 55% of Stanford's students came from California.)
Those are just a few off the top of my head. I don't disagree that moving for work plays a role but back in the 1930s lots of people moved around the US for work (more than today) and work was far more all consuming (having only 2 days off the entire year was not uncommon, e.g. working every weekend, no breaks). And loneliness appears to have been less prevalent then than now.