Think of semi-structured documents, where you have a list of pre-defined sections. I've seen it in use by insurance companies for case reports, in real estate for appraisals. And of course we've all seen it work well in the form of HTML. There's some structure to all of these examples, but mostly for annotating text sections. You need some flexibility built into the schema to add fields as needed, but you're not dealing with various map / list / primitive data types as a matter of routine. Just making this one up, but if LaTeX wasn't already the standard, I'd also use it if I was digitizing the content academic papers, for instance. You have an a header with metadata, abstract, the body, citations. There's some structure, a need to add some metadata, perhaps flexibly over time, but mostly it's just a document.