Mystifying argument: HTML vs Microformats

I can't help but feel that this debate is about tradeoffs, rather than absolutes. But here is an intersting argument:
Dare Obasanjo aka Carnage4Life - Using XML on the Web is Evil, Since When?:

" If everyone invents their own tags and attributes, pretty soon you get people calling the same thing by different names and different things by the same name. "

"Didn't the XML world solve this with XML namespaces like six or seven years ago?"

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Didn't it solve one of those 2 problems?