I've been told by more than one old pharmacist that the reason they're called "cabinets" is because the ice cream was kept in a freezer they called an "ice cream dipping cabinet" back in the old days.
They looked like this:
http://www.webstaurantstore.com/exce...27-6-cu-ft.jpg
http://www.cnelson.com/files/images/BDF8_09.JPG