The issue here, is that there is still exclusivity in such a poly amorous arrangement. (Which is distinctly NOT the same thing as "Mom has a new fling every week")
This means long-term social association with those persons, and long term potentiation of those relationship webs. This is definitively NOT "I just want the sex, not the relationship" levels of casual sex, which is what I am against.
You are interjecting your own bias here. Please be aware of that. I am not at all interested in some church pusher's agenda. I am not some crypto-apologist for poisonous worldviews that come from religion (which do not descend from reason or data, but come from "GOD SAID SO!! OBEY!" instead, and any time you try to dictate reality like that, bad things happen.)
The metastudy stated that while polyamorous relationships are very common in human social groups, even among those populations there is a major pairbond in that grouping, between 2 people, statistically.
You are attempting to get "Orange" from "Fiji apple, and Macintosh apple."
You can't get there. Casual sex is an orange. Polyamorous relationship is a fiji apple. Monogomy is a macintosh apple. While both the orange and the fiji are sharper tasting, the orange is not equivalent to the fiji.
Since this forum tends to be analogy challenged--
Casual sex is explicitly defined as "Not permanent relationship". The practitioners are AFTER this "NOT A RELATIONSHIP, JUST SEX" nature. The biology of humans is to form long lasting social relationships, and sex is a very profound biochemical mechanism to form those relationships. The relationship hierarchy is simply larger in the polyamorous group, not chaotic. It is always the same individuals, and there is long-term retention of individual relations. This is why both monogamy and polyamory are "apples", and the casual sex is an "orange." They are fundamentally not the same thing. The neural repatterning happens, when the brain stops forming those relationships, because it has to keep pruning relationships from its associations networks (because the indivuals are never seen again.) Once that repatterning happens, it becomes much harder for the person to have a DESIRED patterning. In the cases of "repeat booty calls", that association is retained, and a "relationship happens ANYWAY." which is why such arrangements "Get weird", basically always, and why the notion is a lie.
That is the argument.
Not "MONOGMY! OBEY JESUS! ONLY ONE PARTNER EVER! OMG! SECHS IS BAD!"
Please dispose of those notions. They are not what I am peddling here.