I'm quite new to containers, but it seems to me that Docker revolutionizes sysadmin the same way npm revolutionizes Javascript. It's not that it magically makes your problems any easier to solve, it's that it lets you declare your solution in a formal way without unstated dependencies, and then distribute your solution in a way that lets others declare a dependency on it.

(More broadly I feel like this same thing has been happening in various parts of the IT landscape over the past few years, to the extent that their ought to be a name for it, if there isn't already?)