A vitriolic debate has engulfed what’s typically an arcane corner of immigration policy: the H-1B visa for college-educated foreigners. Proponents say the visa is an essential but insufficient pipeline of global talent for hard-to-fill jobs — jobs that have long been part of the lifeblood of the American economy. Critics say visa holders are stealing jobs from American workers and driving down wages. The profanities both sides have lobbed across social media obscure their agreement that the H-1B...