XML is for data-exchange, competing with JSON and others. So I have no problem putting it to the data-documents, even though it's more a frankenstein. But HTML is an office-document, used for freetext, nobody really should use it for data, even though sometimes it's used that way.

XML is also used, literally, for office documents (Word, Excel, etc).

So are JSON and YAML. The point is whether you have a programmatic and structured handling of a document's content, or whether it's random, where every line and word can demand for a different parser.