> I suppose it helps to see precisely who is paying for an advertisement, but I don’t think this is actually useful in a real sense.
Think from the perspective of an advertiser. Earlier, an advertiser could pay for any ad anonymously. Now any ad you want to show can be traced back to you. This is a meaningful difference. Even if you as a viewer can't pinpoint the specific person behind an ad, they are not completely anonymous anymore (to Google, to law enforcement that may have a warrant, etc). Of course, this change comes at the cost of a reduction in freedom from the lack of anonymity.
Think from the perspective of an advertiser. Earlier, an advertiser could pay for any ad anonymously. Now any ad you want to show can be traced back to you. This is a meaningful difference. Even if you as a viewer can't pinpoint the specific person behind an ad, they are not completely anonymous anymore (to Google, to law enforcement that may have a warrant, etc). Of course, this change comes at the cost of a reduction in freedom from the lack of anonymity.