Posting significant events in your life, from birthdays to weddings and promotions, is a social media staple. But Jenny, like many other Britons recently, has hesitated over contributing to the infinite scroll. “I wouldn’t have even posted my wedding really,” she says. “But I had to because … There’s like an etiquette. Nobody else can post your wedding until you’ve posted. So my friends were like: ‘Please post, it’s been like a week.’” Peer pressure aside, the 32-year-old is not alone. Britain’s communications watchdog reported last week that UK adults were becoming less active on social media platforms. Ofcom said...