You can't resell a game in steam because Valve doesn't let you, not because the game is being made artificially scarce. Which it is, but this is not the reason you can't resell it. The point is that reselling an NFT doesn't require a central ledger. The central ledger is necessary to prevent the same token from being sold multiple times by the same seller. In other words, to create the illusion that the seller doesn't have something (and therefore can't sell it) when in fact they actually have it.