Not everything is in a container, and not everything is easily containerized. Sure, in development you can hook your application up to a mocked-up database, but what if you've got an actual production database that requires authorization for your application to talk to it? Or what if you need to change Route 53 settings because you're doing a blue-green deployment of containers in AWS? What if you need to set up networking between two containers on different hosts, but the two hosts can't even talk to one another?
I was always thinking "Ansible vs. Docker" when the answer was "Ansible + Docker." 💜