Think about it from the other direction. Julia makes writing certain types of programs much easier than in other languages traditionally used to build app GUIs

Think about it from the other direction. Julia makes writing certain types of programs much easier than in other languages traditionally used to build app GUIs. This then makes it possible to wrap those programs in a GUI for distribution. If you're wrapping a GUI around a CRUD app then Julia probably isn't your best choice. If you're writing a novel differential equation solver and want to provide a GUI for people to explore it then this makes it possible to do so.