XML has a bad rap because people went a bit (ok a lot) overboard with it in the early years, pretty much like what happens with a lot of other technologies, but as far as structured and human-readable data formats with good schema and tooling support go, it's pretty much unbeatable. Now that JSON is the New Good Tech and XML is the Old Bad Tech, too many developers use JSON where XML would absolutely make more sense, and then we end up with unholy abominations like Portable Text, which is JSON pretending to be XML, and is so incredibly verbose and monumentally stupid that it feels like some sort of joke esolang data format rather than something being used in a production system. But no, here we are, god is dead and JSON is XML.

XML is terrific for building eg. structured markup languages with more complex markup than what something like Markdown can provide, and have the resulting files be comparatively readable, at least in comparison to the JSON-based alternatives – compare HTML to Portable Text, for example. XML has such a bad reputation – partially deservedly – that people just automatically assume it's not a valid tool for anything modern, even when the modern "NoSQL", "structured and typed data is for nerds, suck it" JSON solution is a giant pile of shit compared to the XML alternative