Two things can be important for an audience. For most, it's the race condition lesson. Locks are there for a reason. For AWS, it's the stability lesson. DNS can and did take down the empire for several hours.
Nobody is saying that locks aren't interesting or important.
The race condition was necessary and sufficient for collapse. Absent corrective action it always leads to AWS going down. In the presence of corrective actions the severity of the failure would have been minor without other aggravating factors, but the race condition is always the cause of this failure.