I adressed this point in my previous poll so I didn’t think I would need to do it again:
A South American dlc could cover an area going from the Muisca in Colombia to the Mapuche in Argentine (hell, some people even want one single dlc covering Meso AND South America), while Europe already has such a civ density, any new addition would likely be super specific. I think LotW was a fluke, with both civs being in very different parts of Western Europe (and even then, the Sicilians are very Norman focused so it was arguably a French dlc).