Because like most people who have something to say about Burning Man, this guy only understands half od what he's talking about.
The principal constraint has nothing to do with moving vehicles off the playa. It is Washoe County road 34, which is a narrow, poorly-graded two lane road that goes to Gerlach, there it joins with Nevada SR 447, a wider, less poorly-graded two-lane highway that runs through a town of less than 500 people. From there, it's still 90 minutes to Interstate 80.
Old US 49, Jungo Road, cannot be used by 99% of the vehicles at Burning Man, although those of you looking at the Google Maps are already thinking you've got an answer.
The 'answer' is: Don't plan anything - including being at work - for the Tuesday after Labor Day. Or leave before the Man burns. And if you're going out, consider volunteering to help the Gate, Perimeter, and Exodus Crew. Lots of good people work for free (or nearly so) to make sure the flow into and out of BRC stays as efficient as possible.
Another note: stereotyping anyone's lifestyle or motivations for attending Burning Man is an exercise in being an idiot. (Except for the feather headress-wearing Coachella fratkids. Everyone at Burning Man HATES those assholes.)