It is a truism that Marketers will pay less when they receive lesser value. The reciprocal is also true -- as you impair marketer effectiveness, marketers will pay less or shift spend to outlets that offer a better return on ad spend (ROAS). Each of the following proposals are scored by different dimensions that impact how well they support marketers’ ability to achieve effective outcomes from their advertising across publishers.

SWAN's scale and cross-publisher optimization makes UID2, Contextual and Publisher 1P data solutions more valuable and actionable.
While providing great cross-device recognition capabilities, hashed email solutions lack scale and the ability to offer view-through attribution and lift measurement to marketers.
Privacy Sandbox
Privacy Sandbox offers scale, but fails to provide accurate engagement, cross-publisher frequency capping or lift measurment.
Contextual provides great engagement capabilities, but does not meet other aspects of campaign optimization from frequency capping to lift measurement.
Pub 1P Data
Publisher 1P data provides great engagement, but its value is directly proportional to scale. The lack of cross-site portability not only fragments marketers' media buying, but also does not meet cross-publisher frequency capping or lift measurement.
Clean Rooms
Clean Rooms provide great analytics, but do not provide cross-publisher frequency capping or cross-site optimization.
Differential Privacy
Differential Privacy can provide scaled analytic solutions, but does not support smaller publishers given the lack of accurate engagement, cross-publisher frequency capping and real-time optimization.