> Surprisingly, almost no one wears their headphones all the time while coding.

The author should try reading Peopleware. Here's an excerpt from Chapter "Bring Back the Door":

"In response to worker's gripes about noise, you can either treat the symptom or treat the cause. Treating the cause mean choosing isolation in the form of noise barriers -- walls and doors -- and these cost money. Treating the symptom is much cheaper. When you install Muzak or some other form of pink noise, the disruptive noise is drowned out at small expense. You can save even more money by ignoring the problem altogether so that people have to resort to tape recorders and earphones to protect themselves from the noise. If you take either of these approaches, you should expect to incur an invisible penalty in one aspect of worker's performance: They will be less creative."