This would also be highly useful for defining a variety of on-scroll events even without having an on-scroll trigger. As scrolling is moving content through the viewport along the Y or X axis, variables could then be assigned to the position of various elements.
Look at the progress bar in this thread for instance – if you wanted to recreate it in a prototype with X and Y variables, you could assign an Y variable to the top of the thread and define conditional statements for set increments. "If scroll-variable == -120px set variable progress-date to “July 2023"”, you get the gist. The possibilites would be endless!