You're referring to the Scientific American spectrum-coloured article? If they had tried to make it a handbook of DSDs it would have been impossible to fit in a double-page spread. The fact they didn't include some of the others isn't relevant. The article's purpose wasn't to be completely comprehensive, but representative. It still doesn't mean sex is a spectrum. (Again, there's a difference between "attributes" - how something appears - and what it actually is.)