In defense of simple architectures
https://danluu.com/simple-architectures/
for most kinds of applications, even at top-100 site levels of traffic, computers are fast enough that high-traffic apps can be served with simple architectures, which can generally be created more cheaply and easily than complex architectures.
It's interesting that he argues that a Kubernetes-backed app running graphql is a "simple architecture"; I'm not disagreeing but it reinforces to me that what "simple" means is extremely context-dependent.
"Simple" often means "things that are reasonably common knowledge on our team".
A corollary of that is that, by education and practice, you can change what it means for something to be simple! Simple is what you do, and what you do is what's simple as long as it's well understood.
If it's not well understood, by which I mean that deep understanding of the system is either not present at all, or not well-distributed among your team, then that's what complexity is.