Because it is worth repeating
Because you are too stupid to know just how stupid it was the first time,
Capital is a result of labor, and is used by labor to assist it in further production. Labor is the active and initial force, and labor is therefore the employer of capital.
Henry George
and pray tell that does that disqualify the op? economics is based on the management scarcity, labor is no more or less a force employed and /or manipulated by scarcity.
capital may be created by labor, capital is also created by say, soybeans.... labor can become scarce, so can soybeans, the correlation is same, labor becomes scarce via better production methodology, education, loss of skills, or lack of such in some certain econ. or geographical climates.
You Marx et al wish like the Clayton act wish to argue so as to disconnect the economics which commands the result of the manipulation of scarcity to find a political platform, ( as Lincoln did) from which to make the model of economic mgt. somehow unfair, greedy and or harmfully manipulative. good luck on that....