What the hell are they even talking about here? Since when has ANY browser been "Fully, 100% W3C Compliant"?? Answer: None. Ever. Seriously.
There are rafts of non-compliant features, both legacy and newly introduced, in every single one of the most popular modern web browsers. (Even Opera!!) Certainly, with the last decade of popular support pushing Browser Vendors towards W3C compliance, the web has been more standards-based than ever before.
But this is just a silly argument. I agree with the political aim of the EFF here. But let's not just invent things or misrepresent things. It makes them lose credibility in my eyes.