Why is the fact that important? If a unidirectional bezel is knocked and accidentally moved on the dive, it could only display a longer underwater time. Meaning the wearer will overestimate rather then undervalue immersion time, and in cases that require decompression stops, This may be a make-it-or-break-it variable that https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/