Let me see what I can remember from my Psychoanalysis class 25 years ago (it laregely backs up Whitlock).
Freud said certain men who enjoy watching others with their wives have what he called a Tendency to Debase. Why? Because, having been raised by saintly women, they tended to identify heavily with their mothers, especially if their fathers were domineering (ol' Buddy). Thus, having married a woman who became in essence a mother substitute, they had a great deal of difficulty having normal sex, since the mother's saintliness and purity was transferred to the wife. in order to get their rocks off (my language, not Freud's) the man would need to take his wife off the pedestal, have her debased in his eyes, so as to get those love juices flowing again.
This seems like a textbook definition of the kinds of things you saw on Rex's BDSM alt.sex page, including things like defecation, etc.
When this was exposed to the outside world, it screwed Rex up mentally. He's been inflicting wounds on himself and his team ever since in reaction. Why? Because he's a sadomasochist who actually enjoys the pain!