I think JW's are just like anyone else. Certain personalities tend to attract others and people naturally gravitate toward those who have commonalities or similar personality traits.
The difference is, JW's boast about how "different" they are and how much "love" they have among themselves. They set you up to expect more from them than they can actually deliver. This high expectation level is hard to live up to and people continually disappoint one another. In a culture where it's OK to shun anyone who is doing wrong in your eyes, it's easy to carry it over toward those who have simply disappointed us as well.