The same way you're describing sysadmins knowing how to look at a linux system and understand what's going on. I feel exactly I can jump into any app and troubleshoot on k8s. And I draw on a lot on top of my previous sysadmin exp.
The debugging? Not really. It comes from sysadmining. But k8s is a standardized way to deploy software amongst a fleet of machines. Which makes it easy to debug complex systems because I know how to access it all.