Unlike a standard .iso or .wbfs file (note the lowercase extension), the WBFS format was a partition type. You couldn’t just drag and drop games onto a drive. You had to use tools like WBFS Manager for Windows to format the entire drive to WBFS.
If you were modding consoles back in the late 2000s, three letters will send a shiver of nostalgia (or frustration) down your spine: . wbfs wii games