The only objection IMO would be if Apple allowed their own ads platform to have different treatment. Then it would look like Apple using platform power to manipulate the ad market.
Watch to see if they have the notification for News or other apps that show their app install ads which seem to use data, not as much/well as FB, but still tracks users and for sure tracks install conversions
It is not about ads, it is about tracking across apps.
...which in turn is about ads.
Right, but tracking being about ads does not make showing ads equivalent to tracking, although Facebook wants you to believe that.
IOW, (A => B) does not imply (A <= B). Or (A <=> B), for that matter.
Based on Facebooks history of choosing profit over ethics, I wouldn't be surprised if they decide to productize surveillance of citizens to authoritarian governments, if they haven't already.