I think the major problem is that it's easy to fill yourself into thinking that you could have stopped it in hindsight because you already know what happened.

If you took this one report more seriously you would have stopped it, sure, but how does that help you going forward? It's the same kind of thinking that makes you feel like you could have made a killing buying Microsoft stock or Google or something. Easy to make a post hoc rationalisation that explains the observed facts, likely impossible to do ex ante.