If the complaint is that Google's first-party properties are giving information about the user to the ads department behind the scenes, then address that directly, as an anti-consumer behavior, rather than saying "you have to make sure your browser supports other companies' anti-consumer behavior too to be fair".
It's pretty widely agreed as being acceptable for sites to advertise to their users based on those users activities on the site. For example, if you read a lot of NYT news on investing the NYT might choose to show you investing ads while viewing other NYT news stories. The same goes for Youtube and other Google properties using first-party information in first-party advertising. I haven't heard people claim this is anti-consumer behavior?
First-party and third-party advertising are to some extent competing for the same advertiser dollars. An advertiser could pay to advertise on Youtube (to Youtube's audience with Youtube's information: 1st party tracking) or with Google Ad Manager on many smaller sites around the web (to those site's audiences with Google Ad Manager's information: 3rd party tracking). I'm just giving two examples here, and there are lots more in both categories; YouTube is an example of a site with a big 1st party audience and its own ad system, but so are Instagram, TikTok, Reddit, etc.
Since Google has a large 1st-party presence, competition regulators have raised issues with them making browser changes (removing 3rd-party cookies) that would have a side effect of shifting advertising dollars from 3rd-party to 1st-party contexts.
