Rumpelstiltskin offers the miller's daughter/queen a way out of her contract to give him her baby if she can guess his name. This riddle element of the story, Zipes points out, is a device to build and hold suspense -- the name itself has no meaning. So how does the queen discover that name? Her servant observes the little creep chanting, "Rumpelstiltskin is my name!" Given that clue, it didn't require advanced study in forensic science or cryptography to figure out what his name was.
Capital's self-disclosure is slightly more subtle than Rumpelstiltskin's – but not much. Instead of prancing around and chanting "the real measure of wealth is disposable time," capital enforces a transparent taboo against any such resolution. When I say "capital" I am referring to a being no less fabulous than Rumpelstiltskin but nevertheless representative of actual social relations. Capital spins straw into gold through an employment system. But for the mechanics of that employment system to remain hidden it must also continually spin golden theory into straw man dogma.
"All models are wrong," wrote George Box, "but some are useful." Note the subjectivity of utility. Some models are "useful" precisely because they are wrong. Others are presumed wrong because they might be useful to the wrong people. In his reply to the New York Times debate question "Was Marx Right?" Brad DeLong wrote, "I have long thought that Marx's fixation on the labor theory of value made his technical economic analyses of little worth." Marx's "fixation" is a figment of Brad's imagination, with a long and disreputable tradition amongst authorities whose familiarity with Marx's writing is second or third hand. On the contrary, Marx was arguing that Capital fixated on labour time as a measure of value and that such a fixation was its "moving contradiction":
"Capital itself is the moving contradiction, [in] that it presses to reduce labour time to a minimum, while it posits labour time, on the other side, as sole measure and source of wealth. Hence it diminishes labour time in the necessary form so as to increase it in the superfluous form; hence posits the superfluous in growing measure as a condition – question of life or death – for the necessary. On the one side, then, it calls to life all the powers of science and of nature, as of social combination and of social intercourse, in order to make the creation of wealth independent (relatively) of the labour time employed on it. On the other side, it wants to use labour time as the measuring rod for the giant social forces thereby created, and to confine them within the limits required to maintain the already created value as value." (Grundrisse, "Fragment on Machines", Folks really ought to read the whole thing.)
Marx was writing critically about a fixation. That's different from having a fixation. Was Marx wrong about Capital's "positing labour time as sole measure and source of wealth"? That would be difficult to prove definitively but a long history of strenuous opposition to the reduction of working time is evidence in favour of the proposition.
Remember that shorter working time was a prime objective of labour unions up until at least the middle of the 20th century. It could be argued, I suppose, that resistance -- organized resistance -- from employers was simply irrational but that doesn't say much for the Homo economicus thesis. Nor does it say much for the academic economists who have cranked out facile but disdainful rationales for dismissing shorter work time demands.