A lot of the W3C specs are actually so poorly specified that none of the browsers can even figure out how to implement them. E.g. in CSS the width of a pixel is

A lot of the W3C specs are actually so poorly specified that none of the browsers can even figure out how to implement them. E.g. in CSS the width of a pixel is defined relative to the length of each user's arm. Once upon a time the W3C site pointed out that they did not define standards. They offered recommendations with the idea that people would implement them, see what worked (or didn't), and at some point a standards body (ISO, ECMA) would issue the actual standard. However, so many people keep referring to W3C recommendations as standards (mostly as a way to brow-beat people into following one or another preferred practice) that the W3C changed their tune and decided to go along for the ride. Instead of seeing W3C TRs as the last word we would be better served if people viewed them as (likely) incomplete works-in-progress on the way to ironing out well-defined standards.