@cuchaz I'm biased, so take this with a hefty handful of salt...
Advertisers *really* want data and despite it becoming ever more difficult to lawfully obtain data, the big brands are generally still satisfied with the volume and quality of the data they are collecting.
There is a real apocalypse moment approaching when 3rd-party cookies are killed in Chrome.
Google are *really* pushing for Enhanced Conversions, which is passing (hashed) PII to ther platforms (Google Ads, DV360...
@cuchaz SA360 and now even GA4). The tagline is "this gets around the requirement of 3rd-party cookies because we *already have* user consent for this data sharing".
This only really works for a user who logs into an account on a website or otherwise provides (at least) an email address.
All the users who don't log in, buy something / convert aren't contributing their data in the same way. This is probably what Firefox are trying to fulfil. Chrome is testing similar.
My devil's advocate...