I'll agree with your agreement; the human legibility of XML data often leads the novice programmer into making bad assumptions about the simplicity of implementing XML.

While it is possible to implement "well-formed" XML easily enough, validating against schema is another matter. In this particular article's case, the "well-formedness" isn't even there.

For one-off, transport xml it's not much more. It's proper escaping, declaration with character set and not using features you do not know how to use. First two are solved by using proper library, third - by common sense