Wikidata can (and probably will) store information about each moon of Uranus, e.g., its mass. It does probably not make sense to store the mass of "Moons of Uranus" if there is such an article. It does not help to know that the article "Moons on Uranus" also talks (among other things) about some moon that has a particular mass: you need to know what *exactly* you are talking about to exploit this data. An article on "Moons of Uranus" could still (eventually) embed Wikidata data to improve its display, but this data must refer to individual moons, not to the article as a whole.
The problem I see is that you have no definition to which real object the data are tied. We agree that the problem is not the interwiki links per se. It is what results from it. How do we tie data to a wikidata page when we don't know what it is about?