This is purely my experience and it is based on observations that are nearly two years old. Your mileage may vary. And since I've heard that Docker is much more

This is purely my experience and it is based on observations that are nearly two years old. Your mileage may vary. And since I've heard that Docker is much more stable, I plan on giving Docker another try (though on a side project) within the next six months. That aside, the shortest possible answer is that Docker added significant amounts of complexity, without providing enough utility to make that additional cost worth it. As an example, at the time (I believe this has been fixed), you had to make sure that every machine that would work with Docker containers was on the exact same version of Docker. There was also significant overhead associated with making sure that the code inside of running containers was actually running. Finally, we found that some of the services we ran just simply didn't work well with Docker, so our deployments quickly became a mess of "this is Docker" and "this is raw." Getting into Kubernetes certainly made Docker a more smooth experience, but that opened up another side. For me, the further I went down the Docker/Kubernetes path, the more I realized that I was implementing my own PAAS...at several times the cost of just using someone's PAAS!