The question was (paraphrased) "what value does blockchain add over SQL database table with a unique index?" - not whether NFT issuers are more trustworthy than trusted organizations or if NFTs are a valid asset class.
But it isn't the same, with NFT's the trust comes from the NFT issuer and not the blockchain. With bitcoin you just have to trust the chain, but with NFT's you have to both trust the chain and the issuer.