Blanks are dangerous in other ways because in some peoples mind they turn the gun into a play thing as happened in the original subject of this thread. In my home town two fools were playing around with a shotgun and blanks, one of them decides to slip in a live round to prank his friend with the kick. Guess how that ended. Remember the news story about the french soldier who sprayed a crowd with what he thought was a magazine of blanks? Bottom line, militant nerds need to take a lesson from sword and sorcery nerds. That is, if you're going to have pretendsy play time don't use real weapons. That is the exact purpose and reason why toy guns are made.
Also, and this is irrelevant to my point, blanks made to be used with blank adapters in military excercises are much weaker than blanks designed to be used without a blank adapter. As the blank has to have sufficient power to cycle the weapon without the aid of a plugged bore. So it is concievable that like the french soldier, the person in the original article of this thread may not have realised he was shooting live rounds until it was too late.