I've seen someone put this into action, and open communications with his subordinates' wives. Instead of getting mad at her husband for being paged in the middle of the night, or having to work weird hours, she can angrily text the boss directly.
Anyhow - the purported direct benefit, according to Alex St. John, is for "the wife or GF" as the whole point is to make her happy (from the linked presentation: "If the wife or GF is unhappy the engineer is gone").
Hence, my question: how does it help the wife to directly interact with her husband's boss? Put differently, what is it about directly interacting with her husband's boss that makes her happier than directly interacting with her husband?