Mark Robinson, who easily won North Carolina’s Republican gubernatorial primary on Tuesday, has the misfortune of having spent years on Facebook without thinking about his future political career. The current lieutenant governor of the state—and the first Black man to hold the position—was a furniture manufacturer who was launched into politics in 2018 when he gave a viral pro-gun speech at a city council meeting in the wake of the Parkland school shooting. Two years later he was elected to his current office. He will face Democrat Josh Stein, the state’s attorney general, in the general election in November. The...