We are human beings. We are embedded in a massively complex social context, and within this context there exist many powerful sources of reasons. We are social creatures: The roles we play, the relations we enter into, the norms we accept, and the ideals with which we identify are constantly interacting with our practical thought, our judgment and our action. We are also organisms with basic needs: the mere fact that we are embodied generates an enormous number of important practical imperatives for us, individually and collectively. We are also citizens: we live under laws and institutions that shape our prerogatives and which can provide reasons for action on their own. We are also goal-driven: a human life is probably not complete without the active pursuit of coherently organized ends...But what if some of those standards aren't actually standards? Take the assertion that "a human life is probably not complete without the active pursuit of coherently organized ends." That is profoundly arguable! I'm a hedonist. I think, when push comes to shove, that someone who has no coherent goals to speak of and plugs herself into an experience machine for her entire life will have acted in her true self-interest. She's not goal-driven at all but she's living a better life than I'm living, despite all my goals. Smyth, I assume, will contest this claim. But to do that he'd have to give an account of why there's more of value in life than hedonic well-being. And many people have! But such an account, I think, is likely to be a ethical theory of the kind Smyth finds largely useless.
Gee, look at that! No moral theory, yet somehow we can still speak of acting for good reasons, we can still praise and blame one another, and we can still hold each other responsible for what we do according to various standards.
Or what if these standards conflict with each other? Jean Valjean had reasons to steal bread deriving from loving his nieces and nephews and wanting them to not starve. He also had reasons to not steal bread deriving from being a French citizen. Are the former reasons stronger than the latter ones? I think so, and if it came time to defend that position I'd note that the good caused by saving childrens' lives outweighs the harm done to the producer of the bread. But what does an anti-theorist say? I suppose he could say that it's just the case that Valjean has more reason to steal the bread. What kind of monster could say otherwise?
But this kind of intuitionism is (a) itself a kind of theorizing and (b) only takes you so far. Peter Singer and Peter Unger have argued very convincingly that if you share intuitions like this one about Valjean, you are also committed to giving away most of your income to UNICEF or Oxfam. Even if Valjean's rectitude is obvious, the Singer/Unger position is not at all obvious, and if it's the case (as I think it is) that you have to support both or neither, then ethical theorizing is necessary for us to think clearly and consistently about these sorts of problems.
I suppose my point is that the best kind of ethical theory draws on precisely those resources that Smyth presents as alternatives to ethical theorizing. It doesn't deny that there's such a thing as being a good uncle or being a good citizen but instead tries to piece together when being a good uncle is more important than being a good citizen, or what other beliefs we are committed to by virtue of our beliefs about what being a good uncle entails, or how the kinds of "good" we're talking about in these cases are connected to one another.
I also think it's worth distinguishing the kind of "realism" about ethical theory's limitations that Bernard Williams argued for (and Smyth is echoing here) from the skepticism of people like me about the role of this kind of academic theorizing in real-world political debates. I doubt that recapitulating arguments from Living High and Letting Die is going to convince anyone in the House to vote for more foreign aid or more open borders, and it might in fact alienate potential allies, but I also think that's bad and that the world would be a better place if more politicians and people in general acted on the basis of well thought-out ethical beliefs, while also accepting that people with different beliefs (like, say, Rawlsians and utilitarians) can and should work together when those beliefs intersect (such as on increasing government aid to poor people).