Safari and Firefox already disabled third-party cookies a while back. There’s no problem with that, right?
"But Apple's and Mozilla's moms let them disable third-party cookies" isn't likely to be a winning argument in court when the major Western competition authorities threatened you in advance with anti-trust action.
I agree that what you say should be true. But it is not, and I've already posted the sources to show it in my first message in the thread. Do you think the sources are fake? Or do you think that all those regulators are just joking around, and when Google does something they expressely forbid, it'll just be laughed off?
But even if not, Chrome makes all kinds of API calls to the Google backend, independently of browsing. It would be trivial to e.g. upload the browsing history there and associate it with the user's Google account.
[1] https://www.theregister.com/2020/02/05/google_chrome_id_numb...
The Topics API is intentionally much less capable than 3rd party cookies. So if Google phased out 3rd party cookies and replaced them with Topics, the abilities of non-google ad networks would already be curtailed. Meanwhile, the same restriction doesn't apply to Google as they can just have the browser track users in much the same way as 3rd party cookies used to do.
So even with Topics, there would be a power imbalance between Google and other ad networks.
So unfortunately the "neither" choice is not an option here.
[0] https://arstechnica.com/tech-policy/2021/06/eu-antitrust-reg...
[1] https://www.gov.uk/government/news/cma-to-keep-close-eye-on-...
[2] https://www.engadget.com/google-antitrust-doj-cookies-privac...
[3] https://www.theverge.com/2021/3/16/22333848/google-antitrust...