Why Don't You Use Web Content Accessibility Guidelines; WCAG 2.0

I'm writing a paper on what is hindering the adoption of WCAG 2.0 and though I have a number of factors in mind already, I would like the document to be as comprehensive as possible.  

So I'm hoping maybe people here can give me further insights into the factors you think are hindering the adoption of WCAG 2.0.  

Thanks in Advance,

MSc HCI student at University of York - Adam Roethenbaugh.