Gaining culture through killing is quite edgelord or Robert E. Howard territory, and even quite disturbing as a notion. I would definitely say it did not work that way for the Aztecs or Spartans. The Spartans eschewed the trappings of high culture, and were always FAR below the other Greek polities in the matter, so obviously mass killing wasn't doing anything for them there (in fact, Athenians often rhetoircally portrayed them as,, "displined barbarians who somehow spoke Greek,"), and the Aztec cultural style was only something that spread, as it did, in the context of the Mesoamerican sphere - and, even then, it was more than just racking up body counts.