As Taylor Swift will know only too well, hardcore pop fans are the most terrifying force ever unleashed upon the internet. Photograph: Cassidy Araiza/The New York Times “You are a simple people,” The 1975?s Matty Healy declared from the stage at 3Arena in Dublin last January. Delivered in the singer’s deadpan leer, the observation was in response to an impromptu chorus of “Olé, Olé, Olé” emanating from the sell-out audience. He wasn’t the first visiting pop star puzzled by Ireland’s love for “Olé, Olé, Olé”. “Are you still singing that?” Noel Gallagher sighed at the Olympia in 2011. Hilariously, Beyoncé...