That sounds like they are just talking about the rental version, but maybe some retail stores still have the boxed versions of Office (for) Mac 2011, the ones that just contain a code.
If you have an older version of Mac OS X, you will still be able to install Office for Mac 2011 for a limited period of time. If you have an active Office 365 Home, Personal or University subscription, and Mac OS X 10.10, you can install Office 2016 for Mac. On the Microsoft Store - Office FAQ page, there is a 'Can I install Office on my Mac?' question under 'Office Download and Install'. It looks like Microsoft has decided to require Yosemite (or later) for Office 2016.