They started tightening things up in the mid-'90s. Previously the standards hadn’t been at all rigorous and there wasn’t much or any national cohesion, but then National Geographic and other popular press started sponsoring major technical expeditions like the Wakulla and Huautla caves, and profiling pioneering cave divers like Bill Stone, and suddenly there was a problem of amateurs thinking they could do these extreme dives at a time when there was no formal training. Also there was the 1994(?) death of Ian Rolland, who was diabetic. He had surfaced, but he passed out in shallow water, his rebreather came out and he drowned. It was always assumed he’d passed out because he was low – interesting what @MichaelS says about “feeling disconnected from the diabetes.” So everybody wanted to ensure nothing like that happened again.
That’s exactly how it was done outside the Navy too. Sheck Exley wanted to figure out why so many divers were dying in Florida caves in the '70s and '80s and started analyzing their dives so other divers could learn from the mistakes. In 1986 he wrote (and typed and photocopied and stapled) “Basic Cave Diving: A Blueprint for Survival,” the first safety manual and the foundation for all safety rules that came after.
A wrist computer that talked to a CGM would be very cool.