I attended a panel at SXSW a few years ago called “F*ck Standards” which was all about breaking from standards when it makes sense. There was a Google engineer on the panel who talked about the Google home page failing validation, using deprecated tags, etc. He said it was all about performance. He specifically mentioned layout rendering with tables beating divs and CSS in this case. As long as the page worked for their users, they favored performance over standards.
This is a very simple page with high traffic so it makes sense. I imagine if you’re building a complex app that this approach might not scale well.
From the horse’s mouth.