The idea of Linkin Park, a group from the era of Limp Bizkit and Papa Roach, trying to present themselves as venture capitalists might sound like a story that The Onion briefly toyed with after the first dot com bust only to discard because of its implausibility. But we live in a different time now — a time when the musician mogul is a powerful role model. Jay-Z acquires music streaming services and Nas invests in dozens of startups and Ashton Kutcher backs founders of major startups while...