Well yes, technically it's all data that is being downloaded and parsed by your browser, one way or another. I think people mean to say that tables are meant for displaying tabular content, and not really meant for layout.

Of course they can be used for layout. When I got started building sites, there were no other options! But divs and css are really a more flexible system.

You can do a "wordpress like" two column layout with table, sure. But it's harder to maintain. For example, with a div/css based layout you can do some impressive things - like custom stylesheets for printing or totally changing the look of a page by just including a new stylesheet.