Teotihuacan was not built by the Aztecs.
Teotihuacan (which we know very little about) predates the Aztecs by quite a few centuries. It was not altogether clear that human sacrifice in central Mexico occurred when Teotihuacan controlled that area. This is a brand new discovery.
That's interesting news. Even though I have an avid interest in history, I've largely ignored the history of the Aztecs, Mayans, and other civilizations of the western hemisphere.