The rule is in place because the crowd generally pay to get in to the concert and it isn't very pleasant to see a sea of cameras at the front rather than the artist. It is out with our control that idiots in the crowd hold their iphone up the whole show though I am afraid! The flash rule is in place because when you have 20 lenses flashing in an artists face from 2 feet away, it can be a distraction and becomes easier to have a no flash rule than trying to coordinate minimal flash use. Believe me when i say it is nothing untoward photographers, every artist I work with appreciates them being there, but it is a solution to a conundrum of paying crowd vs working professional.