There's huge difference between manually setting up load balancer - let's say HAproxy - and being able to just declare in an application that it needs "this and this configuration to route HTTP traffic to it."

The time I spent managing HAproxy for 5 services was bigger than the time I spent managing load-balancing and routing using k8s for >70 applications that together required >1000 load balanced entrypoints.

It's a lever for the sysadmin to spend less time on unnecessary work.