It seems to me that a reflective statement (a la motivational interviewing) is inherently revealing of the orientation of the clinician who states it. A complex reflection - one that is not just a rephrasing of the client's own words - adds to the client's statement by switching words out and adding in a small interpretation. This interpretation can vary wildly between therapists. Some will talk about the client's thoughts; some, their motivations; others their core values and meaning in life.
It bothers me that some people call motivational interviewing their "theoretical orientation," because, as I have written previously, it is not one; it is more a technique. The reflection that MI uses really shows the underlying theories that the clinician holds dear to them. I do think that we should not discount MI, though, because it does operationalize how to actively listen to clients and is, in my opinion more of an offshoot of client-centered therapy than anything.
In this light, I guess it would be difficult to call even client-centered therapy a complete psychotherapy, because its practitioners mainly use only one technique (active listening). When only one techniques is used, it seems to me that theory is pretty much technique-less and is more an avenue for a theory than a theory unto itself. In the same way, I guess that many people would point the finger at existential therapy and say that it is only theory and has minimal technique (I would like to say that CCT is a good personality theory, but in the realm of therapy, falls somewhat short because much of the theory falls flat when used in session; hence the minimal technique). My rebuttal here is that existential therapy's technique is both very present and invisible. It is present in being present-focused, critical, and always thoughtful. It is willing and able to explore all the subjects that the client would like to understand. It is invisible in that the technique is so parallel to the theory that it is often difficult to understand that it exists, especially apart from other theories. I also like to view it as a pair of eyeglasses that one forgets he or she is wearing but one that constantly informs his choice of phrase and approach to an issue brought up.