Apple isn't the only online advertising platform, and they don't have anything close to a monopoly there. They are free to build their own ad tech and keep it to themselves, or give themselves preferential access.
Using your dominance in one industry like that could fall afoul of anti monopoly laws.
People make a lot of to-do about it, but, that's not really an unusual thing in the market anymore. Sony has exclusive control of their store, does not permit sideloading, and no, the hardware isn't subsidized.
https://www.extremetech.com/gaming/325504-sony-finally-turns...
Regardless of whether you feel that's also bad, it goes to establish that this is not unusual or particularly noteworthy behavior.