I've been looking at some information architecture stuff for OrderCloud recently, and came across a situation where "groups" were suggested as helpful for the business scenario I needed to model. There didn't seem to be a great deal of documentation about why you might want them for things like this, so I figured it might help others for me to write down what I was looking at. And why groups might be the right answer for you too...
If you're experimenting with OrderCloud then getting a sandbox instance is an important part of the discovery process. Unlike most of Sitecore's products, this one is available free to anyone (just register in the portal) - so it's easy to give it a try. But if you want to build an experiment against the sandbox instance you need your code to authenticate with it. And this has tripped me up a couple of times because it's not wildly well documented. So learn from my frustration...