It’s got a lot built around it that JSON doesn’t have an equivalent for.

I still miss XSD and WSDL for a lot of cases. Other cases it was serious overkill where JSON is a better option.

XML isn’t superior. It’s heavier but more complete.

JSON is lighter and less complete.

Everything in code is always about trade offs. The error comes when people advocate for one solution all the time.

If you're going to reach for automation, why not just use a binary format like protocol buffers, flat buffers, capn proto, etc? You get the tooling and a ton of performance for free.

JSON is great because you don't need tooling. XML is great because it's expressive. You don't need expressiveness for a data format, but it works great as a markup language.