Many of them could never handle the complexity of writing an entire app and maintaining the backend running on 20+ Linode VMs without the support of a trillion dollar corporation.
You really overestimate the skill and complexity of most code written by “FAANG” engineers.
FWIW, I’ve been coding for a long time (the 74 is a hint) and I started at 12 writing assembly language and spent a decade writing C including maintaining a proprietary compiler/VM for Windows CE devices.