Since inception, Amazon has achieved nearly unprecedented growth of revenue, profits, employee head count, customer base, product offerings, and just about any other business metric.
You believe all of this was achieved with mediocre talent? I doubt it, but maybe you're right. Either way, so what? If Jeff Bezos has figured out how to create an innovative, world leading, ultra high performance business with mediocre talent, his accomplishments (vis-à-vis Amazon) are even more admirable.
Given that they can only hire mediocre tech talent, this speaks to perhaps the success of the HR management that they were able to build what looks like a market leading offering in AWS (the scale of which is absolutely huge - all built by these mediocre engineer!)
Performance, as I say above, is the point. Amazon pushes very hard for performance. Achieving high performance is difficult and uncomfortable. But to classify the activities which yield high performance as "cruel" is an interpretation. This article and the NYT articles it cites bend over backwards to paint Amazon in a negative light in this respect. But here's' the thing, Amazon is very transparent about both their aims and means. Amazon encourages and incentives workers to quit bc Bezos (quite correctly, in my opinion) recognizes the "march to mediocrity" as a basic reality of large orgs. Amazon offers training which will help employees find different jobs and pays quit bonuses. Flat out: that's not cruelty. It is actually a fairly humane and "progressive" approach to a difficult and uncomfortable challenge.
Implicit in these claims is of course (the fairly absurd, in my opinion) belief that there are some more effective means of achieving sustained and very high performance that are more comfortable for employees. This, to me, is the root flaw in the "cruelty" interpretation. It basically requires us to be believe that Amazon is run by sadistic people that are aware of better means by which to achieve sustained high performance, but that they choose more uncomfortable, "less humane" options instead. If I'm wrong, I simply ask that the people on the other side of the argument point to proven methods (that they interpret as not cruel) which yield the kind of sustained high performance that Amazon has achieved.