Let me be clear; I was mostly talking about ratings re: SNR. Ratings, in a very explicit mathematical sense, become literally undefined when you aren't comparing them
between things, but just comparing something to itself. You can't have a vote with one candidate; you can't have an auction with one bidder; etc. The results are all undefined. In the exact same sense, you can't have a ratings system in a marketplace with one product in it.
Or, for a direct analogy: you can't have Hot or Not where it's just one dude. Is he hot? Is he not? Undefined.
Now, freeform text reviews: sure, they might hold some meaning, even in a single-seller marketplace. (For subtle behavioral-economic reasons, I would hypothesize that they probably don't, but let's pretend they do.) I would posit, though, that whatever's in those reviews is already the result of "PR sterilization." What you're seeing is what Apple wants you to see. It's their store.
Reviews only "work" (i.e. have guaranteed real signal, rather than "maybe real, maybe fake" signal) when incentives in a marketplace are aligned such that even the marketplace owner has no incentive to tamper with which reviews are or are not visible. That is not true here, and so the reviews are not, and never were, trustworthy. They were noise from the start.