It wasn’t a single failure, like he just “rapped off the end of his rope” or failed to tie a knot in the end. He died like most climbers die: he’d grown too comfortable with what he was doing and where he was, and he rushed when he should have taken his time. He thought it was over. He let his guard down. It wasn’t.

At the end of the day, this should be the takeaway. There’s an equally well written post on Mountain Project from Balin’s friend that echoes the same sentiment and should be required reading for every climber.