XML suffered from the verbosity of having both open and closing tags and the weird uncertainty around attributes vs. child tags, but the real problems came from consultant-driven programming wanting to put XML everywhere and use if for everything. Ant & Maven. SAML. XML for configuration and DI frameworks. *ML everything. Did you know there was a thing called VoxML[1]? Basically XML for phone menus (remember those? Press 1 for English, Press 2 for ... Press 9 to hear these options again).

SAX was the hammer applied to every problem.

1. http://xml.coverpages.org/voxML.html