But that concern is kind of the point. Again, my take on rule zero and why it is important is so you can accommodate what the players are trying to do. I am not saying this is the one and only way, that rule zero is the only way to conceptualize it, but there does seem to me to be something in play in RPGs where by their nature you kind of have to go beyond the rules, bend the rules, change them, etc if you really want to prioritize the ability of players to fully inhabit their characters and the setting.
Sure, like I said, there are plenty of ways people approach this. I don't think I would say it is likened to santa clause though. It is just a handy way to describe the fact that the GM and the players are not beholden to the text when the text is disruptive, feels strange to what is going on, or just doesn't make sense. And this is something that crops up naturally in play, whether rule zero is explicitly stated or not. Like I said, since I first started playing it was a phenomenon you saw, even in the most comprehensive systems, and it was something I personally welcomed.
All that said, some people don't like this. I get that. And I am not saying there is anything wrong with ditching rule zero and taking another approach (I think it is likely rule zero will still emerge in various ways, but if you can find or build a system that satisfies you and doesn't need it, I say that is a good thing).