Their superior genetics, not good technique, enabled them to lift enormous poundages in the three powerlifts. Never do a rep in the deadlift if you can't perform the rep with good technique. Never round your back when deadlifting. Going to failure in the deadlift should be defined as the point when you can no longer perform a repetition using good technique. I have known quite a few lifters who have injured their low backs during a set of deadlifts because their technique went out the window when they started to get fatigued.
Many lifters overtrain the low back and coupled with poor technique it becomes a deadly combination.
I was in hover mode at 550 in the deadlift for a long time. I decided to start deadlifting once every two weeks. The result was a new personal record and long time goal of 600 pounds. Lifters who are just beginning to deadlift can get away with deadlifting every week. For the advanced lifter, I believe deadlifting every week will eventually result in overtraining of the low back, especially if the lifter is squatting hard.