My very first website had a tables-based layout, using HTML that I wrote in Notepad. It was a subtle redesign of the homepage for Montana People’s Action, a low-income grassroots membership-based organization that fought for social and economic justice issues.
One reason tables-based layouts should be avoided is because managing a series of nested tables gets increasingly complicated. Not only is the practice considered non-accessible, but it is inefficient and unnecessarily difficult to maintain. Reworking the website for Montana People’s Action in 2004 was a great confidence-builder for me and pointed the way toward me learning about CSS for keeping presentation rules apart from the content itself.