LONDON — Years before the rise of Instagram, Banksy figured out that the key to real influence lay in not in being famous, exactly, but in being anonymous. The mystery of his identity has long been part of the value of his art, which for decades and across continents defied authority from public walls and self-shredded on the auction block. Now, Banksy’s apparent unmasking by the Reuters news agency has generated talk about whether the works themselves retain their cultural and financial value. It also raises the question: Why pop the red balloon of his mystique in the first place? Many Banksy fans mourned the loss of the mystery and lashed out at the news outlet. One said it was like being told without warning that Santa Claus doesn’t exist. “I feel like they are telling me how a magic trick is done,” said Thomas Evans, a Denver-based artist on Instagram. “Sometimes I just want to enjoy the magic trick.” But some art experts say the murals and the message will survive Banksy’s naming because his appeal wasn't driven solely by his anonymity. He and his works — mischievo