I'm sure there will be many who won't agree but, in my opinion, this goes way beyond just diving accidents and who is responsible.
We have, in my humble opinion, cultivated a mentality in our society where many of us no longer believe that we are responsible for our own actions, our own mistakes, and yes even our own lives. Much like the mentally of "I don't need to work because the government will take care of me".
So, when something bad happens to us or something doesn't go exactly according to plan, instead of asking "how can I fix this and how can I prevent it from happening again in the future", many of us are thinking, who else can I blame and how can I make them pay for my mistake. The fact that this conversation has gone on as far as it has is proof of that.
Of course there are going to be times when someone else's careless mistake ends in tragedy but, did they intentionally do something wrong knowing full well that someone might die? Highly unlikely. Yes, in cases of clear negligence, where someone dies as a direct result of that negligence, they should be held responsible. But, those are few and far between.
The vast majority of all diving incidents are the result of a lack of attention to detail by the diver or an intentional violation of safe diving practices. As divers, regardless of everything else, we are responsible for our own safety. And pointing fingers will not bring back those who are victims of their own carelessness.