Google said they would rank sites that use tables for structure lower than they would rank site that used semantic HTML and CSS.

However, CSS has, in the past, been extremely annoying to use if you want a simple tabular layout to your web site.

As other's have, or will point out, the table tags can end up being more data that you'll download each time the page contents are sent, whereas css, if you do it correctly - in a file external to the HTML - will only be downloaded one time, saving bandwidth and time.

If the site's author doesn't care about the SEO demerits of using a table, then she's not going to spend the time converting the site. This has the side effect of annoying semantic HTML purists, who believe that the HTML should only describe the content and only CSS should be used to apply styling.

While the semantic+CSS camp has a fair point, I will admit to being driven near raving mad trying to make CSS do things that were dead simple using a table. So I empathize with the people who don't want to spend large amounts of time figuring out how to make CSS do what they mean.