I have often observed a style of refutation that seems destructive, and those that practice it seem to become unwitting sophists. I hope to sketch its general form here and provide an example.
The context of these refutations includes a first step where an activity is accounted for in this form, "whenever you are doing X, all you can really be doing is Y." It is immaterial for the purposes of this discussion how one has gotten to this conclusion, and these sorts of conclusions are not the target or our suspicion.
The problematic move is when this sort of conclusion is used (implicitly or explicitly) to refute (or dismiss) some group of practitioners of activity X in the following way: these practitioners of X are doing X incorrectly because they haven't recognized that they are really doing Y.
The problem with this refutation, is that if the only possible way to do X is to Y, then whether you acknowledge it or not, when you do X you do Y. From this we cannot say that X was being done incorrectly, but that X should be seen in terms of Y. An example may help to explain why this is a problem.
Rorty tells us that there is no such thing as an essential meaning of a text, and that all one can do in interpretation is to use a text for some purpose. We can assume that Rorty has given a sufficient justification for his position. Now, Rorty sees essentialists as readers of texts that seek an essential meaning, and says that they are incorrect because texts don't have essential meanings, they only have meanings relative to purposes one uses them for.
It appears that Rorty wants to have things both ways, for either essentialist readers are interpreting, which means they must be using the text for a purpose, or they aren't participating in interpretation in the sense Rorty is describing and there is no matter between Rorty and the essentialists on this point.
If the essentialists are using a text for some purpose, then this purpose should explain why essentialist readings look the way they do, and we would also see that they are practicing interpretation perfectly well.
The problem here is not with Rorty's view, but with his combative attitude which seems to put him in a rush to make a hit. I imagine this attitude as being fostered by a particular culture of philosophy that seems most satisfied by the setting up and knocking down of positions. This sort of interest in attack and defense perhaps makes it easier to blunder in the above manner.