::cough::
A few years ago, I did pretty much the same thing myself. Thankfully the late summer was our slow season and the site recovered pretty quickly from my bone-headed move, but the split second after I realized what I've done was bone-chilling.
I think just about everyone has thought at some point that they understood how something worked, only to have had things go pear-shaped on them.
The lesson: people are not fully knowledgeable about everything, even the smart and talented ones.
"You would not believe the sort of weird, random, ill-formed stuff that some people put up on the web: everything from tables nested to infinity and beyond, to web documents with a filetype of exe, to executables returned as text documents. In a 1996 paper titled "An Investigation of Documents from the World Wide Web," Inktomi Eric Brewer and colleagues discovered that over 40% of web pages had at least one syntax error".
We can often figure out the intent of the site owner, but mistakes do happen.
If you're writing HTML, you should be validating it: http://validator.w3.org/
Is there any real downside to having syntax errors?
The web would have died in stillbirth and it would never have grown to where it is now.
"Be generous in what you accept" (part of Postel's Law) is a cornerstone of what made the internet great.
XHTML had a "die upon failure" mode, and it has died, why do you think XHTML was abandoned and lots of people are using HTML5 now.
The irony of that statement on hacker news is pretty amazing. Have you looked at how the threads are rendered on this page. It is tables all the way down.