The first U.P. combined road bike speed plus go-anywhere capabilities to start a whole new category. Now original U.P. features such as dual wheel size compatibility and a dropped chainstay are the standard for performance gravel bikes.
So the position lets you get out of town and reach the gravel/dirt/trails quickly (unlike a mountain bike). Space for big tires lets you tackle any route (unlike a road bike). And you can do that with one type of tire for everything or finetune your ride with multiple wheelsets or tires.