Using Docker as a local development system (especially with boot2docker on OSX creating a bunch of containers with different major versions of OS (el6/el7 for example) and being able to develop/test multiple apps at the same time is the only benefit I can justify for Docker.

But that's as far as I will take it, Docker is mainly used (from what I've seen) as a nice way to package something without having to write an actual package (RPM/deb) that will work across multiple platforms (for the most part). If you take the time to learn how to properly package your application, docker is unnecessary in almost every case.