There really is no argument as to what it is called. It's merely a discussion about how Americans were brought up with the name, not knowing that is was NEVER The British Open. We know now, but old habits die hard sometimes. More than likely, it was the actual 1st Open of any, in golf, so they want to distinguish the fact from others.
How I will explain this to my hometown crowd is beyond me. Most in that little burg probably do not even know there is another golf tourney in the world. 🤣 Damn hillbillies. How'd they ever learn the game to begin with?