The welding on large German warships was actually defective. Several of them suffered catastrophic failures which led to the loss of their stern (including Bismarck). Lutzow, Prinz Eugen and Scharnhorst all suffered similar failures. Bismarck's armour scheme was also antiquated, and several inches thinner than contemporary British battleships.
There is still a strong belief, especially in the UK, that German engineering is superior to anything else - the British Army called this "BMW Syndrome" when trialling successors to the Challenger 1. After they found flaws in the turret armour of the Leopard 2, its supporters in the army still refused to accept that a German product could be anything less than materially perfect.
This feeds into assertion that Bismarck was scuttled, therefore clawing back a "victory" for the Kriegsmarine. I wonder if the supporters of that particular theory would then accept that the Royal Navy could equally claim that HMS York, Exeter, Sheffield, Sir Galahad, Ivanhoe, Encounter, etc. were not sunk by enemy action
