If you mark-up content as a table, you're making a claim about what kind of content it is (you're labelling it as tabular data). If you use a table-based layout, you're falsely claiming that your entire site consists of tabular data.

A question for those who still use tables for layout: Is it that you don't care about accurate mark-up, or that you think there are practical problems that justify the use of inaccurate mark-up?