I've used Rancher and while it is very nice it still punts a lot of the hard bits like interacting with the outside network, vm creation, and storage (especially shared persistent storage) to the ops team to figure out.

Creating a big-ole cluster of app servers was never really the hard ops problem which is what k8s does really well.

Creating the cluster of servers isn't the value of kubernetes. We all had clusters of servers well before k8s, openstack, and things like AWS.

The benefit of k8s is the orchestration of those clusters. Spinning up 6 new http servers and getting them added to the load balancer automatically. Generating 4 new memcached nodes and getting them registered in DNS so clients pick them up and add them to the hashring.

The benefit of k8s is the scaling and elastic capabilities. It can trigger vertical scaling by spinning up larger pods or horizontal scaling by adding/removing pods.

Anyone thinking that people are using k8s because it can create app servers doesn't understand why anyone is using k8s. If all we needed to do is create a cluster of app servers, we wouldn't be using k8s.

That being said, a cluster of app servers still needs orchestration and config management and we had a ton of crazy solutions for that prior to k8s.