The rarity is tied to the Blockchain. You cannot just "copy" an NFT, that is one of the main reasons they exist in the first place.
Look, I agree that it's DUMB, in 90% of it's use cases. But I also feel it isn't much different that physical cards which really have no feasible limit. Magic COULD print several tens of trillions of cards a year if they wanted to. But this is part of the scam. They only print a certain amount to make people spend more money.
For example. The new Lord of the Rings magic set has a card The One Ring. They are printing a single alternate art version that is ONLY in $100 Collectors Packs.
Is that any better than NFT's. No THEY BOTH SUCK.