Imagine if instead of kneecapping XHTML and the semantic web properties it had baked in, Google had not entered into the web browser space. We might be able to mark articles up with ``, and set their subject tags to the URN of the people, places, and things involved. We could give things a published and revised date with change logs. Mark up questions, solutions, code and language metadata. All of that is extremely computer friendly for ingestion and remixing. It not only turned search into a problem we could all solve, but gave us rails to start linking disparate content into a graph of meaningful relationships.
But instead Google wanted to make things less strict, less semantic, harder to search, and easier to author whatever the hell you wanted. I'm sure it has nothing to do with making it difficult for other entrants to find their way into search space or take away ad-viewing eyeballs. It was all about making HTML easy and forgiving.
It's a good thing they like other machine-friendly semantic formats like RSS and Atom...
"Human friendly authorship" was on the other end of the axis from "easy for machines to consume". I can't believe we trusted the search monopoly to choose the winner of that race.