Can re-stringing hurt your guitar?

Dear Bill,
I am having what's turning out to be a rather heated debate with a few of my friends on the topic of re-stringing an acoustic guitar. They are saying that you should NEVER take off all the strings at once, but rather change them one at a time. They think that removing all the strings at once is somehow detrimental to the guitar. Having built a few steel-strings from your book, I say "hogwash". Take off all the strings if you want. It won't hurt a thing.

A note from you on this topic would settle it once and for all. 

A "heated debate" about how removing all the strings are "somehow" detrimental to the guitar, huh? Anybody advance any...evidence on their side? I did'nt think so. It must have been battling Beliefs.

The Belief most likely originated from rather good advice for players of all TAILPIECE instruments (violins, cellos, arch-top guitars): if you take all the strings off, the bridge falls off! —and in many instances, the soundpost falls, too. This useful tip apparently jumped at one point from one instrument world to another, starting as sound advice on violins and arch-tops and becoming dopey advice on guitars. The skewed information subsequently got handed down uncritically from teacher to student over the years and thus became generally enshrined as a Belief. By the way there are dozens of similar religiously-held myths among players/teachers/makers—like, never cut the strings. "It damages them" I heard. I should try to list them all some time.

I also love watching proponents "reverse engineering" a justification for a myth! That is, they start with a myth, and then create an elaborate set of highly logical and credible reasons why it must be true. A quintessentially human trait. 

Musical fascism

60 Minutes on CBS interviewed Andres Segovia during the 1980s. During the interview he was asked, why he played the guitar. His answer: "I play the guitar to save it from the Flamenco players."