Jem Aswad Senior Music EditorFrom the Beatles to the Backstreet Boys to Billie and BTS and beyond, the teen-centric pop concert is both timeless and definitively contemporary, from the screaming and sing-along/shout-alongs to the masses of similarly dressed fans — looking almost military in matching merch — to the indulging attendant parents and, these days, the selfies and social overload. And it was the latter, along with the overwhelmingly pre-drinking age audience, that made Olivia Rodrigo’s concert at New York’s Radio City Music Hall on Wednesday the most definitively 2020s teen-centric concert of all: a near-total, two-hour-long wi-fi blackout in the venue so extensive that Russia could have launched a cyber attack and most of the crowd would have assumed it was simply due to thousands of kids posting selfies and video.