Comment by WorldMaker

UWP apps that work by accident on phones is not a bad strategy, though. Good application design is responsive, same reason responsive became a huge buzzword in web dev. Even if you are just designing with Desktop in mind: there are hundreds of combinations of monitor resolutions and DPI settings, and everyone has their own personal preferences for how they arrange applications on those monitors. Windows apps have always been resizable and there are always people that will want to shrink app windows to tiny phone sizes while they work on other things.