The same argument can be made about Borg. Someone at Google needs to know about things like Juniper switches and hard drive bays. Someone needs to repair or replace defective compute nodes and power switches. Before they had software load balancing, someone had to manage the hardware load balancers.

But the idea of Borg is that all of that's abstracted away for the typical developer. It's the same with k8s. The infrastructure team in your org needs to understand the implementation details, but really only a few.

You can also configure load balancers, IAM groups & policy etc as k8s CRDs. So all that stuff can be in one place in the code base alongside the rest of your infrastructure. So in that sense it does abstract those concepts. You still need to know something about them, but you don't have to configure them programmatically yourself since k8s will do that.