What's nonsensical about it? Slashdot was very avant-garde, so fits well for a term coined in 1999. I agree that AJAX represented somewhat of a technological watershed, but wikis and blogs (which came of age pre-AJAX) represented a social watershed, a much better anchor for the democracy that PG seems to consider only from a technical perspective.
This is from the criticism section of your link, by a Brit who would know better than most:
Nobody really knows what it means... If Web 2.0 for you is blogs and wikis, then that is people to people. But that was what the Web was supposed to be all along... Web 2.0, for some people, it means moving some of the thinking [to the] client side, so making it more immediate, but the idea of the Web as interaction between people is really what the Web is. That was what it was designed to be... a collaborative space where people can interact.
He's also called it jargon. It's not a well-defined term (or at least there are multiple definitions for it).
