My point is that <article> and <aside> are only necessary for one type of document on the web, a blog post or magazine article, so adding a tag for that seems excessive, and shows preference for those formats. While <section> is no more meaningful than <div>, so adding it is unnecessary.

I did try to give an example of an extensible method of semantically identifying page elements which would be meaningful to User Agents (browsers and search engines). While it’s certainly not the best plan in the world, I do recognize the issue.

Adding a way in which everybody can assign meaning to certain tags will create the opposite effect. Browsers will have no clue what it all means and search engines will not even bother trying to make sense of it because it will be impossible for them to do so. The HTML5 spec however creates a standard which can be followed by search engines and browsers without losing flexibility.