I'll admit i didn't read all of either document, but I'm not convinced of the argument that one cannot attribute a failure to a root cause simply because the system is complex and required multiple points of failure to fail catastrophically.
One could make a similar argument in sports that no one person ever scores a point because they are only put into scoring position by a complex series of actions which preceded the actual point. I think that's technically true but practically useless. It's good to have a wide perspective of an issue but I see nothing wrong with identifying the crux of a failure like this one.
The best example for this is aviation. Insanely complex from the machines to the processes to the situations to the people, all interconnected and constantly interacting. But we still do "root cause" analyses and based on those findings try to improve every point in the system that failed or contributed to the failure, because that's how we get a safer aviation industry. It's definitely worked.
Its extremely useful in sports. We evaluate batters on OPS vs RBI, and no one ever evaluated them on runs they happened to score. We talk all the time about a QB and his linemen working together and the receivers. If all we talked about was the immediate cause we'd miss all that.
I'm not saying we ignore all other causes in sports analysis, I'm saying it doesn't make sense to pretend that there's no "one person" who hit the home run or scored a touchdown. Of course it's usually a team effort but we still attribute a score to one person.