“Can you believe these kids?” It’s been a recurring theme of the coverage of the Parkland school shooting: the remarkable effectiveness of the high school students who created a gun control organization in the wake of the massacre. In seemingly no time, the magical kids had organized events ranging from a national march to a mass school walkout, and they’d brought in a million dollars in donations from Oprah Winfrey and George Clooney. The Miami Herald credited their success to the school’s stellar debate program. The Wall Street Journal said it was because they were born online, and organizing was...