Whatever. I’m sick of the disinterested majority pretending real problems don’t exist and actively working against systems that would help more people, more fairly, because they’re not willing to use their imagination and compassion.
Your use of hunter-gather societies is a distraction. We don’t need to lean on poorly understood histories when we have contemporary examples to work with.
Also, “nuclear/extended” is two distinct categories, not one. And “polygamous” is a subset of polyamorous and carries some unhealthy ultra-patriarchal connotations and assumptions (I mean, I’m making some assumptions about what you mean).
Your "I'd rather be born as a random person in modern society than a random person in a pre-historical hunter gatherer society" has no relevance that argument.
The hypothesis we are entertaining here: things that humans have no experience with over evolutionary timescales tend to be bad for us. Ice cream for example, has more sugar, fat and salt than anything humans had access to until very recently; evolutionarily speaking, we have no experience with it. Ditto alcohol and heroin.
Nor is it a particularly well-formulated or convincing hypothesis, your cherry-picked examples notwithstanding. We don’t have evolutionary-timescale experience with medicine, electricity, the written word, or democracy either. How we think prehistorical people groups may have arranged their societies is almost completely irrelevant for modern policymakers, which is what this article is actually about. We have a long list of better ways to make this decision than “Hmm, well, how do uncontacted Amazon tribes of a few dozen people structure things? Perhaps we should just copy that in our nation of 300 million people?”