One thing this misses in the "dictionary" example is that tools (like xpath) push you towards "key in attribute" selection. One of the most common operations we do with dictionaries is lookup by known key, and storing the key in attributes makes it much easier.
"Key in attribute" is the correct way to do it, it's just that his examples are absolutely terrible and make no sense at all. A completely unstructured list of key-value pairs is overkill for any structured data format.
