That's a very illustrative example. It completely and utterly destroys the benefit of having attributes and makes the structure less clear in context of the XML

That's a very illustrative example. It completely and utterly destroys the benefit of having attributes and makes the structure less clear in context of the XML ecosystem. I imagine if there was discipline around attributes being only used for meta-data and maybe explicit (de-normalized) references (which is arguably meta data, happy to discuss), then XML would be semantically richer by default. However like this we are left guessing the semantics if we encounter some XML. Somewhat in contrast, HTML is generally, but not consistently, better at making this distinction, which enables clearer semantics around accessibility, HATEOAS and so on. Ironically we are kicking that value proposition into the can when driving web application rendering with JSON (like popular SPA frameworks do), so we have to re-invent meta data and communicate that with JSON-schema.