Imagine you wanted to run two apps on the same host, and they depended on different versions of those components, and you wanted to be able to install the app a

Imagine you wanted to run two apps on the same host, and they depended on different versions of those components, and you wanted to be able to install the app and its dependencies on a new machine really quickly for scaling reasons, and you wanted an exploit on one of the apps to be difficult to escalate over to the other app from, and you'll start understanding some of the pain points Docker solves. :)