I noted that one reason to distinguish revolutionary and supplementary EC is that they bear different explanatory burdens. So, recall one way that Haugeland argues for revolutionary EC. He argues that the brain is not a component of the cognitive system, since there is no interface between the brain, body, and world. So, this is revolutionary ... rejecting intracranial cognition.
As an aside, one might think that, if your theory of what a system is tells you that the brain is not a component of the cognitive system, then you should check your theory of what a system is. One person's modus ponens is another's modus tollens, after all.