Imagine you run 3 different ruby (or whatever other language) and they all run on different versions of ruby. Containers allow you to easily isolate the whole

Imagine you run 3 different ruby (or whatever other language) and they all run on different versions of ruby. Containers allow you to easily isolate the whole stack including the individual version of ruby and install only the packages needed for that app to run in its own container. Of course it's still possible to do this without containers, my company handles it by building our own custom rpms for each ruby version and sticking them in /opt.