So it was, in fact, designed correctly as an illustration. Either way the context of that comment is "why does XML do this?" when in fact XML, itself, does not

So it was, in fact, designed correctly as an illustration. Either way the context of that comment is "why does XML do this?" when in fact XML, itself, does not. It allows both data and metadata; this is not a flaw, because it is not a pure data format. You can choose to use those features correctly or incorrectly, and how you choose to do it is application-specific, because it is a format that is capable of producing both structured and semi-structured markup. Sometimes an ID is data; sometimes in the context of an application it is only metadata. It depends. And that is putting aside that this complaint was used to mount a partial defence of YAML, which is one of the worst things the open source community has ever done to the world. YAML is never the answer.