Hmm, are markets self-ordering?
I think in the purest sense, just having some form of common currency would be considered "order" - unless you're suggesting that only pure barter is necessary for a functional society - but then even that requires some broad agreement on weights & measures in order to function (e.g. how long is a board-foot? how much flour is 1 kilogram?). Collectively the market must agree on some standards in order to function.
Also, unregulated markets always end in monopolies, with or without a capitalist economy. Sooner or later someone will try to establish themselves as the sole supplier of some good or service. Only active oversight and regulatory enforcement can prevent it.