Ben Smith thought that he’d be spending the end of April banking interviews about his book that goes on sale next week. It’s not working out that way. Instead, the celebrated news maven—who slung scoops at Politico, launched BuzzFeed News, covered media for The New York Times, and is now cofounder of the buzzy Semafor news startup—found himself bloviating on television and podcasts about the firing of Fox News’ Tucker Carlson and CNN’s Don Lemon, icons of a 40-year-old cable news industry that predates the internet. In other…