There is a use case where its really the best solution I've seen so far, say you need to cluster a long running stateful service. Its written in C so making it

There is a use case where its really the best solution I've seen so far, say you need to cluster a long running stateful service. Its written in C so making it stateless is absolutely non-trivial. So simply load balancing won't work. Docker swarm could work but compared to Kubernetes stateful sets who is actually using docker swarm or other clustering technology for scaling stateful services.