Lets take situation #2. X realizes that Situation#1 is possible. So X sells his Rolex to Y but fails to disclose that its blockchain-tracked. Now Y has the Rolex (and is out of some money). Now X-claims that Y stole the Rolex from him.
How does Blockchain differentiate from #1 (where the Rolex should be returned to X) and #2 (where the Rolex should be returned to Y) ? The only way to solve this issue is to ensure that Y transacts on the _same_ blockchain.
Which... isn't the case at all for NFTs, Bitcoin, DOGE, and etc. etc. There are so many blockchains (and each NFT basically makes its own blockchain). It is very easy for X to transact on the wrong blockchain to fool Y right now. (or off-blockchain, by transacting in USD for example).