Well, I had in mind things like, if you're trying to evaluate a flu vaccine or headache medication, you can obviously do much better than a ten year study of all-cause mortality.

But in the context of something like prostate cancer, maybe all-cause mortality is appropriate for people who are already sick, because you are trying to figure out how the risk of death from the disease balances against the risk of death from the treatment, and where the latter may manifest in nonobvious ways, e.g. many people with prostate cancer actually die of heart attacks. Was the stress of cancer treatment a contributing factor? All-cause mortality statistics might help answer that question.