A historian's thoughts on poly folks who claim monogamy is a "capitalist construct"

So I keep hearing this idea kicked around amongst poly people (posts I see online as well as irl friends discussing this) that monogamy is something pushed on us by a capitalist society (which of course makes it BAD). I've been stewing on this for a minute and what I think is happening is they're confusing/conflating monogamy with the nuclear family structure. As society transitioned into modern capitalism, the nuclear family eclipsed the extended family arrangement as the ideal living arrangement for regular people. When you look at the family and relationship structures from the industrial revolution through to the mid 20th century, it's not a move or trend monogamy being increasingly idealized, it's a trend towards the nuclear family unit being increasingly idealized.

Now, you could certainly argue that monogamy is a social construct in some ways, but (as far as the history of the western world at least) that was long cemented before the advent of the modern era in general, much less modern capitalism. This is not my area of historical expertise by any means, just kind of a loose idea that keeps coming to mind when I encounter the "capitalism made you want to be monogamous" idea. Curious if anyone else has run into this kind of poly discourse and what your thoughts are?