I disagree that sorting is the same as isolation. Meeting multiple times per week with a variety of folks isn't isolation, but it's an ideological echo chamber if roughly everyone you meet with is largely like you in demographics, economic status, and belief system.
While there is no one factor that led to MAGA, there are certainly main drivers. I am struggling to see how social isolation led to MAGA (and that lack of social isolation is what led other folks to reject MAGA).
Instead, I would say that a sense of collective narcissism by those who were in traditional American society the "haves" (white, male, heterosexual, cisgender, Christian, etc) has been a main driver of MAGA as those folks, faced with an increasingly multicultural society, have undertaken increasingly extreme actions to avoid relinquishing their prioritized place in American society. To me, it is one of the best answers I've found to the question of, "Why can't MAGA simply live their lives and allow others to live theirs?" Or, more specifically to this thread, why should folks in NC, Arizona, or Wisconsin be so overwhelmingly concerned with the impacts of immigration on a small city in Ohio?