Forum Moderators: open
If the data is not "truly" tabular (that is, it uses tables only for layout purposes) then it can be very difficult to notice, from the code alone, relationships that are patently obvious to the human eye. Like product names and their description or cost, which may be separated by miles of <td></td></tr> in the template. Or headlines and their related story. And so on.
The use of tables for layout was always a kludge - but for a long time it was the only game in town because browser support for even basic <div> and css mark-up was woefully inadequate.
It's still a bit demanding and nutty cross-browser, but it has now become possible.