It's not complex to set up a load balancer in a given specific environment. But it's another kind of ask to say "set up a load balancer, but also make it so that the load balancer also exists in future dev environments that can be auto-set-up and auto-teared-down. And also make it so that load balancer will work on dev laptops, AWS, Azure, google, our private integration test cluster on site, and on our locally-hosted training environment, with the same configuration script." All of these things can be done in k8s, and basically are by default when you add your load balancer in k8s. They can be done other ways, too, or just ignored and not done, also. But k8s offers a standardized way to approach these kinds of things.
Ansible and Vagrant are not perfect, but I think they are far simpler than a single node k8s instance, and more representative of an actual production environment.
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.
