[orthoxerox]

If your XML is written the way people write JSON, then the stack isn't enormous. But XML is usually wrapped in layers of additional complexity. SOAP envelopes and namespaces they require, XSLT that someone invariably used to write an XML transformer, etc.

[XorNot]

Also broken parsers. So many broken parsers. Honestly this is what keeps JSON going: the parser was simple because the language was simple, and as a result any JSON you got basically worked the same way.

Not so with XML: all the parsers were insanely complex with the namespacing and whatnot feature support and possible external URLs and everything else...and as a result however no XML library was ever adequate to interface with anything. On multiple occasions generally the best way to build XML for something was to take a working copy, and then glue text together so you would exactly replicate whatever that specific application wanted, rather then trying to use anyone's library for it.