Hi we have been looking into both Docker and Vagrant at our work place one of my colleagues has already adapted to using this, and it has the advantages with both methods of being able to create and spin up your moodle environments fast.
A good case senario for this would be for new users as they could install Docker or Vagrant and virtual box and be able to spin up their own sandboxed environments of Moodle quickly and easily along with the server they want so in our case CENTOS, and everything else they require, this would take away the need for using XAMPP or WAMP and you could spin up different development Moodles to test different features really quickly.
Another example of this would be if you have a heavily customised moodle with a number of settings which need to be set, you can create your image of this and then every time you need to create a new moodle you can create this from the image which will come with all your settings already in place.
But as I say am new to this and just stepping down this path now so apologies in advance if I have any facts wrong here.
Scott