Twice I've had to deal with outages where the root cause took a long time to find because there were several distinct root causes interacting in ways that made it difficult or impossible to reproduce the problem in an isolated way, or to even reason about the problem until we started figuring out that there were multiple unrelated root causes. All other outages I've dealt with were the source where experienced engineers and institutional knowledge were sufficient to quickly find the cause and fix it.

Which is to say: it's entirely possible that the inferences drawn by TFA are just wrong. And it's also possible that TFA is wrong but also right to express concern with how Amazon manages talent.