My pond has just gotten exponentially more knowledgable

In the general pool of "people who have something to say about Web accessibility," the only reason I don't call myself an expert is because I have a deep aversion to calling myself an expert anything. I am sitting here right now trying to come up with jokes about where I do have expertise -- napping? reading? cat snuggling? -- and I am actually talking myself down from all of them.

I implement and explain the accessibility standards. I test for accessibility on all spectra except cognitive. I write accessible HTML and JS, and debug other people's code. I teach and present on the the bureaucratic, technical, and content aspects of creating an accessible web. I know where my weaknesses are (cognitive accessibility, legal aspects, mobile, etc), but I know where to turn to complement those weaknesses. All in all, I have always been confident in my knowledge in any room full of accessibility professionals.

Then I got involved with the W3C.

Now that I'm co-leading the accessibility folks for the Digital Publishing Interest Group, I'm basically floored every day my how much sheer knowledge there is on the team. Sure, I have a lot in the can about straightforward web accessibility, but there's so much more regarding the interactions between accessibility and digital publishing, and my colleagues know it.