I think starting from the premise that CSS (as it is currently implemented by major vendors) is a super set of tables, and as such, must do everything tables do is misguided. From my experience, the absolute need to use tables doesn't appear in every layout (for me, at least, it's rather rare), and pragmatic CSS developers tend to use tables only as a fallback when CSS / IE / whatever doesn't quite work.

I've seen css examples that can't be done with tables, so I don't know exactly where we are trying to get with this line of reasoning.