"All ratings should be trained in semaphore"
semaphore - we used to call those guys "skivvy wavers"
I'd say all DECK ratings could learn the basics, and they still use flags to communicate on occasion. but yeah, it's not going to help someone in the engine room or a radar operator or a gunner or missile operator.
That and all officers qualifying Officer of the Deck should know basic semaphore and morse. Just because. And how to use a sextant. If they don't know already.