In a more charitable and scholarly mode:
I guess the main thing is that there is no generally agreed upon answer as to the origins of profit within or between paradigms. How many times have neoclassical's tried to redefine capital only to end up in a taughtology over the last 120 years. Yet almost all of the aggregate stats on productivity and profit cite nonetheless employ the basic Q is function of K,L, and a tech residual. Given there is a taughtology in all of this are we then to conclude that nothing interesting can be communicated by aggregate analyses which rely implicitly on such a function?
We could pose a similar such question of other paradigms and their basic analytical framework. Does for example Shaikh's work which transforms national account data into Marxist aggregates reveal something interesting even though it implicitly relies on the basic Marxian view that output and thereby profit ultimately originates in labour? What about the work of Dumeneil and Levy?
If I were to make one point of criticism with the present scholarship on the LTOV it would be that its practitioners have almost exclusively spent their time defending the bloody thing instead of moving on to undertaking empirical investigations and economic analyses.
For those interested in where the state of the debate stands within Marxism, i.e. between Saffrian reinterpretations of the Marxian LTOV and textualist interpretations of Marx's LTOV I would suggest: "The New Value Controversy and the Foundations of Economics" edited by Freeman et al.
The first third of the book takes up the debate and involves a rather intense debate between Laibman, Kliman, Moseley and Freeman. The big disappointment with this exchange is that none of the aforementioned authors' mentions why their interpretation matters for conducting research. That is, they do not tell the reader why one procedure / interpretation is superior to another except that one is said to be more in keeping with Marx or that Steadman and Morishima ( for christ sake even Phil Mirowski thinks Morisha's interpretation was BS) were right. I would argue the debate is stale for that reason and that reason alone.
It would be more interesting at this point if Marxists would just proceed to employ the LTOV and demonstrate the analytical insights it generates as the case may or may not be.
____________________________________ Travis W Fast