There is no debate that smoking causes harm. However assume for the sake of argument that smoking increases one's chances of getting cancer from 10% to 90%. If someone smokes, then gets cancer you cannot definitively link that specific case of cancer to the smoking. When you have a large sample, you can demonstrate the link, but you could still only say X% of people who smoke and got cancer got cancer from smoking; you cannot say who the X% are.
Ah, okay. I think I get that. So OP was saying that we'll never know if anyone got killed by the leaked cables, but someone probably did. I'm not sure I agree, but now I understand. I think some operations may have needed to be changed up a bit, but in the world of espionage... yeah, kinda hard to say exactly what particular action leads to someone getting discovered and killed. It's usually a chain of events, all important in their own way leading up to the conclusion.
That said, I think the path of smoking tobacco --> illness/failing health is more clear than leaked-info --> death.
