Buckeye Trad Hunter, the jury is still out on that statement because it's probably not quantifiable. Until the modern era (whenever that started) we always unstrung our bows after shooting. They hang better on the wall, and they are less likely to be damaged or dry-fired by some well-meaning bonehead who see's it all ready to go.
Perhaps I view it as a task that's actually enjoyable, if not necessary, and it keeps me in stringing/unstringing shape. Also, an unstrung bow takes up less space in the truck.
So this old phart will just keep stringing and unstringing my bows like I always have. You see it's not dangerous if you do it correctly and it keeps muscles flexible. I suppose you can damage a bow while stringing or unstringing, but they don't ship them to you strung so that should tell you something.