Still not convinced. I can audit the message so the only way to game this is we both have to be playing a game. Against who? A third person who we will try to sell afterwards? Same thing can happen in the blockchain as well, no-one can audit what happens off the chain which could be people coordinating.
I don't know what you mean by "audit the message."
Without third-party timestamping or blockchain, the same token can be sold to multiple buyers, and nothing can be used to determine which buyer is the first ("real") buyer.
This is the whole reason blockchain was invented. It wasn't possible to do it at all before that.
