Hi Tiberius,
I can see how you would get the impression that "the underlying assumption is the struggle between labor and capital" because that is the underlying assumption in a great deal of the discourse about labour in a society with predominantly "capitalist" institutions.
That is not my underlying assumption, though. I view labour as a signifier with an object whose boundaries are contingent and to some extent arbitrary. I am concerned primarily with who gets to make the distinctions between work and play (and ceremony, etc.) and between waged and unwaged work and/or play and/or ceremony, etc. and how those distinctions are made, enforced, accepted or resisted.
To do this analytical work and communicate it, I must engage with that discourse whose underlying assumption is the struggle between labour and capital. Otherwise, most readers of my critique would put it down before they got past the preamble. The story of the struggle between labour and capital is one of the recurrent stories we tell ourselves about ourselves that make us who we are.
Another story is the work ethic (or "Protestant" work ethic) myth. In that myth there is no struggle between labour and capital because property is the embodiment of hard work. The struggle is between good and evil in the forms, respectively, of diligence and sloth. Poverty, in the work ethic myth, is the Lord's punishment for idleness, drunkenness and improvidence.
The struggle myth is a polemical response to the work ethic myth. There is, of course, an element of truth in both myths. Otherwise no one would believe either of them. But there is also a sense in which each myth's persuasiveness is grounded in repudiation of the opposing myth. "X is true, BECAUSE Y is false." And vice versa. There is also a good deal of cognitive dissonance in which people embrace both myths simultaneously -- "they are poor because they're lazy; I am not as rich as I should be because I've been robbed by elites."
The polemic also subtly reinforces what counts as labour. Or what accounts as labour. In conventional accounting, nature is valueless until it is appropriated as natural resources. Similarly labour power is without value until exchanged as labour for a wage (or other payment). Treating labour power as a common pool resource requires moving beyond such a selective and distorting accounting method.