The reason we used tables was because getting things right in CSS in the early days across all of the browsers was a nightmare. An expensive nightmare. Which was fine if you were a well funded startup and could afford to rebuild your HTML regularly.
At least though, these extra DIVs weren't disrupting the page layout (eg. when disabling the CSS - something that was still possible at the time), which was beneficial for accessibility.
I still remember the campaign for sites to drop support for IE6 in protest.
I kept our internal reporting site running for 3-4 years, I used CSS for layout.. it required regular maintenance but I had enough time to do it as my main job was as a Database Admin / Data Engineer (I'd have been called "devops engineer" nowadays as I had quite a broad set of responsibilities).