That’s basically what it comes down to: Is your XY plane a piece of paper that you look at from the top, or is it the pixel coordinates of the screen you are looking through?
That’s why X is usually not contested, because it’s the same on a piece of paper that you view top-down and on a screen that you view from the front.
Y is then one of the two potential axies for either a top-down or a side-scrolling view, and Z is the remaining axis.
That’s basically what it comes down to: Is your XY plane a piece of paper that you look at from the top, or is it the pixel coordinates of the screen you are looking through?
That’s why X is usually not contested, because it’s the same on a piece of paper that you view top-down and on a screen that you view from the front.
Y is then one of the two potential axies for either a top-down or a side-scrolling view, and Z is the remaining axis.