If they were talking about Privacy-Preserving Attribution like Firefox is experimenting with supporting on MDN, that would be one thing, but it doesn’t sound like that’s what F-Droid is talking about.
Not only are privacy and data protection founding principles for both Mobifree and F-Droid, the use of tracking-based in-app advertising poses a moral dilemma as well. If someone wants to gain access to an app, but does not have the financial means to purchase it, they can use it at a different kind of price - their user data.
F-Droid is also considering ads that contain no tracking, which removes that moral dillema, IMO:
It should be mentioned that it is possible to include in-app advertising without user tracking. However the lead conversion ratio drops dramatically, so the efficacy of this approach is not nearly as high.
That’s basically what PPA is, advertising without tracking. If advertisers want to pay for it, then great.
Edit: Downvoting without responding like 
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