what advantage does Nike gain for it being decentralized vs everything getting a QR code and you can verify with Nike that the person you are buying it from is the registered owner of said QR code.
Associating one QR code with one shoe is simply not the same thing. Nike doesn't have to make the whole ledger public through give the nature of blockchain, it can be assured that it has not been altered.
Also the thing is not stopping anyone from providing a wrong code. Unless every transaction concerning their shoes is recorded on the block chain, which it won't, and which brings privacy issues.