“Hate” is a dangerously elastic label. And it has long been used to demonize unpopular expression, particularly among people of color. Apple, Facebook, YouTube, Spotify and most other major internet distributors took a bold step this week when they all but banned content from Infowars, a website run by the right-wing conspiracy theorist Alex Jones. The tech companies cited their policies against hate speech for their decision, rather than the trafficking in fake news by Infowars. It’s tempting to applaud this move, but we should be wary. While Mr. Jones’s rhetoric is certainly repugnant, mounting pressure from the political left...