An org chart is a diagram that shows how an organization is structured internally. An organization doesn’t have to be a company, it can be anything at all, when you want to think about how it is organized.
The branching tree structure is a great tool for analyzing or mapping any system or structure: it can be used to break down any system into its constituent parts, showing the relationships between the parts and the whole.
Do you need to think about how the parts of something relate to the whole? Can you diagram it using an org chart?