I don't think their intention was to rob / hide / betray / hoodwink.
> A bunch of PhD traders lost their wealth
That is, the only reason the losses were limited to them was because of special intervention. Otherwise, it would have caused losses for many others.
The kind of situation they were worrying about and rushed to prevent in 2008, IOW.
You are correct, in a trivial sense, that maybe the entire market should have just not trusted anyone else, except perhaps under extreme constraints, which would have amounted to almost no financial intermediation and thus almost no financial industry whatsoever. But even the most hardcore "you should have vetted your counterparty" finger-waggers aren't willing to go that far.