I have huge respect for Doug Crockford, and I never imagined I would disagree with him.
However I think by now we've seen that a lot of that "unnecessary" XML complexity was not, in fact, entirely unnecessary. These days we use JSON for everything, but now we've got JSON Schema, Swagger/OpenAPI, Zod, etc etc. It's not really simpler and there's a lot of manual work - we might as well be using XML, XSD & SOAP/WSDL.
However I think by now we've seen that a lot of that "unnecessary" XML complexity was not, in fact, entirely unnecessary. These days we use JSON for everything, but now we've got JSON Schema, Swagger/OpenAPI, Zod, etc etc. It's not really simpler and there's a lot of manual work - we might as well be using XML, XSD & SOAP/WSDL.