A huge number of cave divers use re-breathers instead of an open system. It gives them much more time underwater and it doesn't create bubbles which in turn can cause the silt in those caves to become suspended in the water taking visibility to zero. Cave divers even kick water differently to avoid this. It only takes one person to start kicking water in panic to screw up everyone in that cave. This is exactly why cave diving requires certification and why many of the entrances have signs telling people not to go in.

Also, the article calls them rescue divers but the more appropriate term is a body recovery diver. It's extremely rare that anyone gets rescued alive.

Edd Sorenson is one of the most legendary recovery divers alive and he has amazing stories about it. That quy has nerves made of steel.