AOE2 variety comes from many different map scripts with many different seeds, not so much from the civilizations/units/techs.
The doc talks about map generations in the AOE2 space section, but given the rational for prioritizing diversity, I expect this the variety in map generation should lead to a higher variety score.
I really enjoying watching the AOE2 tournament scene: https://liquipedia.net/ageofempires/Portal:Tournaments