There’s a crucial scene in Cameron Crowe’s semi-autobiographical depiction of the rock music world in the 1970s in Almost Famous that comes about midway through the film. It’s when the fictional band Stillwater are performing a gig in Phoenix, Arizona. They’re just kicking into their big hit song “Fever Dog,” when guitarist Russell Hammond (Billy Crudup) reaches out to his microphone and gets a big electric shock. He hits the ground, the show ends, and the band storms...