XML can convey a lot more semantic meaning than JSON ever will, and standardisation of things like XPath, DOM, XSLT, etc provides a lot of power when working with XML documents.
With JSON, essentially everything is unknown. You can't just get all child nodes of an object, or get all objects of a certain type, using standard methods. You need to know what object key 'child' nodes are referenced by, or loop through them all and hope that what you find is actually an array of child nodes, and not e.g. an array of property values. Finding all objects of a given type means knowing how the type is defined, AND the aforementioned "how do i get child nodes" to allow you to traverse the document.
Of course that assumes what you have is a document, and not just a string encoded as JSON. Or a bool/null.
My point is, the tooling around XML is very mature. "Use" of a data format is a very broad topic, and covers a lot more than just "i want to get this single property value".