[kjax]

The assumption that small businesses would see a drop in marketing efficiency might assume that advertising costs on Facebook remain constant. In a perfect world, I would think that a reduction in ROAS on Facebook would precipitate a decrease in ad costs, as businesses would be less willing to pay a premium for Facebook ads.

In the long term, I think Facebook is the biggest loser in this scenario, not the small businesses.

[fairity]

I think you're definitely right that Facebook stands to lose the most.

And, I also agree that most businesses will be willing to pay less of a premium for FB ads after this change. But, even for the businesses that adapt their spend accordingly, their final marketing budget will be smaller, and therefore, their net income/profit from ads.