I got denied from Amazon twice, which actually turned out to be a blessing in disguise because I am now the lead dev and architect at a normal older company and I have complete freedom to deliver whatever my users ask for. I literally still can't believe how easy the development process is when you remove all of the BS at FAANG and worse, BigCorp.
Nobody is stupid if they can pass Amazon's interview earnestly. But it is possible to lack motivation and professionalism. That's what I believe Amazon's SWE's are facing.