Using an intermediary for barter is only an "authority" (and thus subject to the whims of a person authority) when barter demands the medium to make an exchange.

I don't disagree with a decentralization, but we don't need to throw the baby out with the bathwater. If there are multiple potential mediums of exchange, it makes hording much less powerful. If there are markets for real barter as well, it destroys the power of money entirely, making it convenient, not necessary.