Anything can become relevant through analogy. Attributes, explicit end-tags, character entities, and validation before processing are acknowledged as worthwhile features in the contexts SGML was originally created for, but the desire to have them in the contexts XML is intended for is compared to an infantile longing to receive the comforts a child receives from a mother, when one is no longer a child and is relating to someone who is not one's mother. Abstractly speaking, an expectation that develops in one context (a tiny infant nursing from his mother's swollen breast) may become ridiculous if it is transferred unmodified into a different context (a grown man who expects women to have breasts larger than his head.)
Analogy works best when it's short and pithy. The amount of text devoted to the 'analogy' should definitely not be allowed to grow several times longer than the exposition it's supposed to illustrate. By then things have gone long past the point where useful rhetorical glossing morphs into incontinent self-absorbed dithering.
