User blog comment:MasterBroccoli/Building categories/@comment-33859014-20190615071924

I agree, you can't categorize military units as "Barracks" or cavalry as "Stable". A unit should be categorized as it's type and perhpas unique units have their civilization tags. But having the building they can be trained at doesn't make sense.

For example in Age of Empires III: The Asian Dynasties, I'll use the Rajput as an example. A Rajput can be trained at the Barracks, Agra Fort, and Galleon. If you were to add those 3 cateogries it wouldn't make sense at all, at least in Age of Empires III's perspective.