Still don't buy it. I have plenty of friends currently in medical school that are very successful and can hold wonderful, non-medical conversations. I do believe you might be on to something for students who are just barely passing medical school. To be fair, most of my friends and I all share the luxury of earning near 4.0 GPAs while not stressing all that much. In fact, I probably wouldn't enter medicine if I felt I couldn't maintain healthy relationships with others because of it.
Maybe the issue is we're telling borderline students that it's important they throw away everything important in life - family, friends, other core values - in exchange for a career. Maybe many students in psychiatry are those same borderline students (based on competitiveness of the field ONLY. Some of my favorite authors and people are psychiatrists, and I in fact also want to be a psychiatrist). BUT, I stand my ground that most physicians are perfectly normal, social human beings.