My zod schemas are 100x simpler than all those SAX parsers I maintained back in the day. Honestly I kinda doubt you've worked with XML a lot. The XML data model is wildly different than that of pretty much every programming language's builtin data structure, and it's a lot of work to cross that bridge.

The article posted here makes a good point actually. XML is a DSL. So working with XML is a bit like working with a custom designed language (just one that's got particularly good tooling). That's where XML shines, but it's also where so much pain comes from. All that effort to design the language, and then to interpret the language, it's much more work than just deserializing and validating a chunk of JSON. So XML is great when you need a cheap DSL. But otherwise it isn't.

But the article you quoted makes the case that XML was good at more stuff than "lightweight DSL", that JSON was somehow a step back. And believe me, it really wasn't. Most APIs are just that.. APIs. Data interchange. JSON is great for this, and for all its warts, it's a vast, vast improvement over XML.

In your situation, I would blame the developers, not the tools (JSON) or fashion.

Even if it's fashionable to do the wrong thing, the developer is at fault for choosing to follow fashion instead of doing the right thing.