The $300bn Google-Meta advertising duopoly is under attack

For the past decade there were two more or less universally acknowledged truths about digital advertising. First, the rapidly growing industry was largely impervious to the business cycle. Second, it was dominated by the duopoly of Google (in search ads) and Meta (in social media), which one jealous rival has compared to John Rockefeller’s hold on oil in the 19th century.

Both of these verities are now being challenged simultaneously. As…