Sure, but whatever they built themselves to accomplish this is also complicated. I know because I have built such systems (and replaced them by k8s).
Hah, exactly. It's not that you can't accomplish all the same things as k8s with your own bash scripts - it's that k8s exists to replace all your custom bash scripts!
But you can still land on top of HN with a "I replaced kubernetes with this 500 line bash script without unit tests" blog article ;)