Joan Didion has had a startlingly active afterlife. A star-studded memorial, a pricey estate sale, an underselling Upper East Side co-op: In the almost two years since her death at age 87, much has been said about the queen of New Journalism—good, bad, and unctuous. The lifestyle coverage can be both a distraction and a deflection from the serious substance of Didion’s reporting on topics from the Central Park Five to wartime atrocities in El Salvador. More than the sunglasses or art collection,