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