As you imply, the hip-bone/thigh-bone discourse is not very illuminating. "Empirically inseparable" is a meaningless statement, where meaning really means something.
I could as easily contradict what you say goes without saying, although you felt the need to say it, by saying that the whole point of the marxist analysis is that finance dominates production. But I have no desire to launch a new faction in marxism, at least not this week.
At any rate, what matters most is not whatever marxist analysis says, but what is true.
mbs
"Mr. Roosevelt is satisfactory to the moneyed interests, he has secretly pledged his administration to do what the financiers (and they are the trust magnates also) want done. . ."
(WJ Bryan, "The Commoner, Condensed," v. IV, 1905)