Right from the twisted start, those who plotted to kill worshipers at two New Zealand mosques depended on the passive incompetence of Facebook, YouTube and other social-media platforms.
They depended on the longtime priorities of the tech giants who, for years, have concentrated on maximizing revenue, not protecting safety or decency.
Many hours after the massacre, a horrific 17-minute video - showing a man in black shooting with a semiautomatic rifle at those running from mosques and shooting into piles of bodies - could still be easily accessed on YouTube.
My colleague, Washington Post tech reporter Drew Harwell, summed up the social-media disaster succinctly in a tweet: "The New Zealand massacre was live-streamed on Facebook, announced on 8chan, reposted on YouTube, commented about on Reddit, and mirrored around the world before the tech companies could even react.