Far be it from me to argue with the unquestionable authority of capitals and bold text, but the metal strip was not by a long shot the "one and only factor that was definately (sic) a cause." There's plenty of causes, and there are plenty of non-approved procedures in this accident, just as in any other one. The difficulty lies in identifying the full causal chain, excluding red herrings (such as the non-factor of wind), and apportioning responsibility.
As for the fuel leak goes, the total flight hours logged by all Concordes was about 300,000 with something on the order of 100,000 cycles. The 737-300 annually logs something like 3 million flight hours in over 2 million cycles. So if the Concorde flew as much as the 737-300 (excluding other variants), blowout incidents with damage would occur daily and twice a week we'd have a punctured fuel tank as a result. How many times that fuel hits something hot or arcing is anybody's guess.
If a smoker chucks a lit cigarette butt off a motorway overpass, he's certainly littering. But if it lands in the bed of a dumptruck hauling black gunpowder in contravention of accepted safety practices, do we charge that smoker with manslaughter?