Technical divers are a funny lot. They compare in many respects to the aviation community, where the norm is to view the death of a fellow pilot as something that he brought on himself by screwing up. Which translated means "If I don't screw up, I'll be fine", which if accompanied by an inflated ego degrades to "I can do that because I am a much better pilot and never screw up".
The difference is that it is to some degree that reasoning is much more true in technical diving and in particular cave diving where:
1. the environment is more controlled than in aviation, and
2. a death is almost universally due to breaking one of the cardinal rules refined through accident analysis - or (lately) due to a rebreather problem.
But the commonality is a tendency toward complacency, a belief that following the rules is going to keep you safe, and a certain arrogance in "knowing" when it is ok to break a rule. Following trhe rules is important but in and of itself it is not sufficient as just following rules will not cut it in all situations. You still need to be actively thinking to stay ahead of the curve on any given dive as depth and time induced stress can seriously degrade your ability to problem solve on the spot if you haven't worked things out in advance or anticipated what could happen and avoided the situation in the first place.
And it can be a fine line. Not running a line from OW to the main line in Ginnie is a commonly broken rule. Post a thread discussing that and you will find both some fairly prudent and reasonable justifications why people do not run a line, but also some significant indicators in some people of serious complacency issues to which they are basically oblivious. (Something I also found in the aviation community). It makes an interesting read most of the time.
There is also an element of the community policing itself. To be honest, not everyone is going to care about a dumb ass OW diver killing themself in a cave, but the entire community does get very concerned about the consequences of OW divers killing themselves in caves if it risks losing access to caves by those with proper training.
In the past the vast majority of cave deaths occurred with divers who had no cave training, or to a lesser extent, exceeding their training. Lately the dynamic has changed as trained cave divers are dying in greater numbers. This is most likely due to many divers attempting much more advanced and extreme goal oriented dives, often after a "too far, too fast" progression in the sport. (Another commonality I see with aviator community is the tendency for young aggressive divers/pilots to push the envelope too far with too little judgement, all to frequently resulting in their death. To many young pilots and divers see themselves as bullet proof.)
So...in the end in any technical diving oriented forum you will get a lot of really opinionated people who often argue with each other but generally still respect each other - once they have each more or less paid their dues and demonstrated that they have an informed opinion based on first hand experience and training.
Until then, it is best to just not try and play in the traffic so to speak. Nod your head, say thanks and just drive on if you don't agree with something - but file it away as the odds are some day the light bulb will come on and you will either change your perspective on it, or at least understand the other perspective and see some value in it.
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I agree with you on the Sheck Exley comment. At least in terms of the lack of evolution that would occur if no one ever exceeded the limits of their training (as opposed to the limits of their ability), or the lack of evolution in configuration and equipment if no one ever tried anything new. The caution here though is that you have to expand the envelope very slowly, carefully and incrementally with full knowledge of what the risks and requirements are.
Exley did an awful lot for cave diving, but his death was, in the big picture, senseless. The risks were exreme, the dangers well known, the margin razor thin, and the benefits both fleeting and essentially worthless. He'd have been far more valuable to the cave community if he had scaled it back a bit and taken a longer view as he frankly would have stayed alive and contributed a lot more to cave diving than just another record attempt.
