The solution proposed for advanced creative review is elegant but does not support the level of granularity needed to meet publisher review requirements.

Imagine an advertisement for fun new restaurant with a creative that exclaims "Celebrate with us!". news-publisher.nyc may feel this ad is appropriate for the nightlife section of their website, but not the obituaries section. Likewise, you can imagine a creative that might be fine on any news-publisher.nyc page but not any kids-corner.fun page. Sometimes the publisher may simply not like the esthetics of the creative and disapprove for subjective reasons.

The free-form "category" described in the proposal could theoretically be extended to support very granular categories that approach the number of domains or even pages on the internet, and be used to list approved publishers or pages, but the SSP would need to be able to inject its own categories for this to be feasible.

However, this approach may require more frequent refreshes between the browser and the SSP as more publishers would approve a given creative over time, unlocking additional qualified inventory.