The whole idea around semantic markup is the separation of markup and presentation, which includes layout.
Div's aren't replacing tables, they have their own use in separating content into blocks of related content (, ). When you don't have the skills and are relying on tables, you'll often have to separate your content in to cells in order to get the desired layout, but you wont need to touch the markup to achieve presentation when using semantic markup. This is really important when the markup is being generated rather than static pages.
Developers need to stop providing markup that implies layout so that those of us who do have the skills to present content can get on with our jobs, and developers don't have to come back to their code to make changes when presentation needs change.