[mntmoss]

Some of XML's biggest achievements lie in written documentation formats(DocBook, DITA) where fine-grained markup control is needed and the presentation of the content is secondary to semantic features like footnotes, indexing, etc. These are formats that professional technical writers turn to when Markdown, Word docs or PDF won't quite do the trick.

For a lot of data, XML isn't the right form and buries too much data in hierarchy and tag soups - but it's flexible enough to make it into whatever you want, and since XML was buzzworded and XML libs were some of the easiest things to reach for in the 90's, it got pushed into every role imaginable.