When news broke that 21-year-old Massachusetts Air National Guard airman Jack Teixeira leaked defense documents on the social network Discord, experts and concerned citizens alike began questioning who vetted this low-level service member who potentially caused grave damage to national security. The Teixeira saga, which will likely play out for years to come across courtrooms, Capitol Hill and the Pentagon, laid bare how a troubled young man with extremist tendencies needed only a computer and reliable home internet to disseminate government secrets. But on a more fundamental level, Teixeira’s leaks represent just the dramatic, final failure of an enfeebled national...