Uh.. If you are trained but break a rule and die it's ok but if you are untrained and die you are foolish??
So, by this line of reasoning, once a cave has been explored, from entrance to terminus, there is no longer a reason for anyone to "re-enact" the efforts of the pioneers and dive the same cave.
Yet people dive already explored caves all the time - what are they doing and why? Do they sometimes wish to run their own lines or make their own dive plans, reverse the route.. foolish.. pointless?
I'd say they are trying to also have the experience of entering the unknown, measuring themselves against a challenge, applying themselves to a task - all of which are completely illogical really (according to your argument) because the caves been done. Are they, or are they not; "Conquistadors of the useless" (who coined that phrase?).
Is it any different than someone who wishes to develop or express the same self sufficiency that other pioneers expressed. People who choose to make their own way in diving without someone else defining it for them every step of the way?
Heck! why go camping when there are so many hotels around these days - darned foolish pioneer copycats