I haven't seen any convincing arguments that it does in humans. If women and men are equally polyamorous, that actually means more sex available broadly speaking, and when you aren't dating to reproduce or settle down forever, your standards can be looser as well.

Now, I don't believe polyamory will ever be dominant, or even mainstream, I just despise the "loser need sex for cohesion" argument.

Say the "successful on Tinder" group of 5%-er men who go to the gym nonstop, and have won the genetic lottery. There is also the "influencer" group of women with countless thirsty men in their DMs. Not every woman manages to become an influencer, but many are extremely beautiful.

Are people in these harems happier being delulu than in some monogamic relationship? I'm not really sure.

Industrialized society has managed to deliver lots of high quality products by replacing the human component with machines... relationships are something entirely between humans however, so they are hard to improve with industrialized processes. Until robotic girlfriends/boyfriends arrive of course :).

If resources are constrained, it’s a toss up if it’s better to have one dedicated partner with a strong bond, or multiple partners with weaker bonds. Depends I imagine on a lot of other dynamics, and if there are kids involved.

There certainly are dynamics where many weaker bonded partners is worth the risk, or prostitution wouldn’t be the world’s oldest profession.

It's loser need marriage.

Somehow I think we've found the sticking point.

Then you have not made a sincere attempt to date multiple partners as a man in the bottom 60%.

Notably, they follow pre-birth control setups and are male centered (one man, many wives), and do indeed exclude large swathes of men from the economy and relationships.

One woman, many husband type setups are quite rare outside of nomadic/pastoral communities.

As to with birth control? Harder to say.

Many<->Many setups seem to have a lot of historical precedent, but mostly in societies without strong property rights (nomadic tribal) as they tend to be unstable over time and unpredictable. No large scale societies exist like that I am aware of.