This argument has been hashed, re-hashed, and re-re-hashed on here a million times -- well, variants of it, at least, such as "HN uses a table-based layout, which offends me".

You can find some here: http://www.google.com/search?hl=en&q=site%3Anews.ycombin...

In particular, pg responds somewhere in this thread: http://news.ycombinator.com/item?id=100460). I might be carefully building a straw man here, as you are speaking to valid xhtml, not necessarily semantic xhtml. I hope you'll forgive me. I think the two topics are related, and that some of the arguments overlap.

The bottom line seems to be "Who cares? It works fine."