Owning the most popular browser, most popular search engine, most popular email platform, most popular ad platform, most popular video platform, etc. They don't need 3rd party cookies. They can mostly reconstruct what was lost.
It takes away more information from everyone else. Widens the gap despite slightly denting what Google can see.
I stick by that. It's not the only move where they tried the boiling frogs approach around widening their control gap. AMP is another example. Manifest V3 also. They've become pretty skilled at making a trojan horse that has an outward benefit with the real intent hidden.
That they end up making concessions here and there to some regulatory bodies doesn't do much to convince me it's all about privacy.
It takes away more information from everyone else. Widens the gap despite slightly denting what Google can see.