Same situation is happening in America, we just don’t call it polygamy because it has been reduced entirely to the physical act.
You can: move to a shack in the wood, be self-sufficient, don't use society's benefits, and hence don't pay taxes. Otherwise society is interested in baby taxpayers, regardless of who's raising them. Even if you don't use roads, your taxes are still used to build them. Ditto with children.
"Poly" folks are overrepresented on dating apps because they never shut their profiles down after meeting someone.
What's surprising to me is how much of it there is. I was on bumble/tinder and a couple of other sites when I was single, and it was so bad the first question I would ask was, "are you poly?"
I don't see any value prop in being poly for a man. Every time I've seen my friends attempt it, the woman is getting laid like crazy, and the man is struggling to find anyone. Imagine dating as a poly man-- what do you tell a woman you meet? "Well, there's no future for us because I have a wife and a girlfriend, but I'd still really like to get into your pants."
And then, there are issues of disease and pregnancy. You're trusting people you don't know to act responsibly as far as disease goes. And pregnancy is a nightmare-- I know a woman who has a husband and two boyfriends, and she turned up pregnant. It was a nightmare for everyone involved. Nobody knew who'd done the deed.
Sex is DANGEROUS.
I will get downvoted to hell for this, but, "poly" is just a modern version of Cuckoldry. If you're into that, that's your business. But all of the ephemera and justifications around it are just thinly veiled nonsense.
In the case of bonobos, there's an Attenborough doc where he literally narrates a scene of a young Bonobo after being mobbed on though I understand it appears fallacious since I can't recall which.
But yeah, social hierarchy is endemic to, at the least, great apes like us, the difference just lies in how we deal with it. The most sexually successful Gorilla males appear to have figured out that you also have to show females that you're willing to give attention to kids even when they're not yours to demostrate real value as a mate, so our part of the animal family tree isn't without its improvements.
I view it more like: the thing that differentiates us from the other animals is our ability to create and exchange ideas quickly (latency) and thoroughly (bandwidth), and those ideas are a state of matter that seem totally dissimilar to our animal bodies. We talk about matter not being created or destroyed, so what is a new idea? What are ideas made of, and where do they exist? I don't know, but I believe my individual dense collection of ideas is my real "human" individual self if that makes any sense.
All of humanity's various -ists and -phobias, on the other hand, seem to be about protecting our animal bodies, the food they need to eat, and the spaces they want to occupy. How much racism has historically stemmed from fear of a group of people in worse financial condition than one's own, coming in willing to work for lower wages thus threatening one's own stability in jobs, housing, food, and so on? How much homophobia (especially towards men) stems from fear of a gay son threatening generational wealth that could historically only be passed to male heirs?
If humanity could collectively lose the need for all of that hate we can still have the "individual", and in fact many individuals at any level you could slice the One. The highest-bandwidth and lowest-latency links are (for now) obviously between the ideas in one's own brain, but similar densities form between people in committed relationships, between close-knit groups of friends, and so on. I just don't see any other path forward now that we humans have spread across the entire Earth and can communicate with any other person in realtime. So much land is "private" now. Where are people going to live? Depopulation should not be the answer, because that's like giving the One a lobotomy. We are all already neurons in a giant brain, like it or not, so I prefer trying to like it :)
Society is so incredibly complicated and interconnected, it's pretty much impossible to say what would happen by changing something.