Not true, as others have pointed out. I rearranged the equipment on my media rack a few months ago, and while the 360 was turned off moved it to a vertical arrangement. Over the next few days, my Civilization Revolution disc started to have read errors; after I pulled it out to clean it off, I noticed a nice, wide ring scratched into the disc from the DVD drive. Moving the console back to horizontal has stopped the scratching, but it won't bring my dead disc back.
I followed the rules and still was awarded with a $60 game that was unplayable.