This go me thinking more broadly about encounter design guidelines and when they became a Thing. I don't really remember how explicit games pre D&D 3.x were about this (and I don't have any books close to hand). I know older versions of D&D hinted at it with dungeon level encounter charts and so on, but it wasn't explicit as far as I can recall. I can't say I remember Earthdawn or Deadlands providing encounter balance formulas.
Was that basically just a D&D thing, and have I so internalized it that I just expect other games to provide those guidelines and systems?