Cave-divers are expected (and taught) to carry reserve gas supplies with them. From the description, they had reserve supplies - enough reserves to search for an hour - but failed to recover their guideline within that time.
The issue was that they lost their guide-line leading to the exit, rather than running out of gas. In such a scenario, no amount of reserve caches could really solve that problem.
Some divers carry a few odds and ends in their buttpacks for longer duration dives, but you never factor this sort of stay into a plan, and don't want to take unnecessary equipment or kit in with you. Where there's been a lot of sump diving (submerged passages between larger air-filled chambers), there are a number of kits like these in some areas, but they're usually left by the expedition and taken back out with them.
The issue was that they lost their guide-line leading to the exit, rather than running out of gas. In such a scenario, no amount of reserve caches could really solve that problem.