My interpretation of what's going on: CEOs finally have leverage against their marketing departments to do black-out testing on social media ad spend. It's difficult to actually measure impact of ad spending, and marketing teams spin results to their advantage. They will observe what happens and re-introduce spending where it actually works.
Conditional on them honestly reporting numbers, it's a pretty credible way to measure effectiveness in terms of incremental conversions you get by showing ads on FB/IG