Our friend links a Mayo Clinic report on weight training and longevity. Big problem is that correlation does not imply causation. I'll never forget the study that correlates eating broccoli with cancer risk.
Anyway, fitness and strength are for functionality, not longevity. Any healthy person can get some cancer or just drop dead from an arrhythmia.
On the other hand, I think it might be true that the eccentric aspect of weight training gets short shrift. Slower is good for that.