Comment by mattmanser

Part of the problem was it came in an era before we really understood programming, as a collective. We didn't even really know how to encapsulate objects properly, and you saw it in poor database schema designs, bizarre object inheritance patterns, poorly organised APIs, even the inconsistent method param orders in PHP. It was everywhere. Developers weren't good at laying out even POCOs.

And those bizarre designs went straight into XML, properties often in attributes, nodes that should have been attributes, over nesting, etc.

And we blamed XML for the mess where often it was just inexperience in software design as an industry that was the real cause. But XML had too much flexibility compared to the simplicity of the later JSON, meaning it helped cause the problem. JSON 'solved' the problem by being simpler.

But then the flip side was that it was too strict and starting one in code was a tedious pita where you had to specify a schema even though it didn't exist or even matter most of the time.