nothing that can beat the feeling of a fresh server install with only the software you need.
However, you do have to consider the cost... in that you'll be spinning up multiple containers for multiple services (if you follow "best practice"), with all of the duplication of resources that entails.
That's the thing though, the fresh server doesn't stay fresh forever because it's not immutable. And any OS will come with software you don't need. I'm just getting started with Docker, but I can see the appeal when trying to deploy quickly and consistently. I'm dreading moving servers because that means I have to re-install everything I need on a fresh server and reconfigure it. If I was using docker, it's pretty much just create a new VM -> install Docker (unless using an image that already has it) -> docker run myservice and done.
@frissdiegurke Knowing what I know now, @julian post can be construed to contain all the information :). I would word it differently though as SSO is probably veyr widely used. And if so, then calling port optional is...well, still technically correct.