Apple is turning its oft-expressed stance on privacy into features that are bad news for everyone from other tech companies to government agencies. When Apple previewed the upcoming iOS 12 and MacOS Mojave at this week’s WWDC keynote, the killer new features that got both developers and users most excited were the ones you’d would expect: the visually stunning Dark Mode on MacOS, the insanely customizable Memojis on iOS, FaceTime group-calling features on both platforms, massive improvementsto Siri, and Apple’s all-new Screen Time digital health tracking tools. All those features deserved the applause they got from the crowd. But it...