After all, although acid welding could create the same effect when it came to forging metals, the actual way it interacted with the materials was very different.
For a very specific reason which would cause problems if he tried to do oracle bone reading using 'acid' instead of 'fire' acid welding was a much more precise affair. You were specifically weakening and breaking down a certain portion of the metal that you wanted to make malleable, whereas fire, although often times following the same principle especially in cases of more modern techniques such as welding, could treat the entire piece of metal without creating trouble or leaving one worrying about the structural integrity of the piece.
