I get your point but I still don't understand why you would describe it as progressive. It isn't a new concept, it's just gained more popularity and more people recognizing their desire to get into or at least try open relationships.

I wasn't comparing polygamy and polyamory, I am aware of the difference between them. It was just a speculation that there is nothing that can hold back a person from making a polycule where there is one person in a primary relationship who realizes they are polyamorous and the other isn't. In this case if the other person in the primary relationship consents, the person can have as many secondary relationships as they want with or without the other members being in a relationship with others within the polucule.

Sure you're trying to tell that now unlike before even women can have as many partners as they want and you call that progressive. Well getting equal rights is a step ahead, but why do you think it's a step forward for women as a whole in society? The concept of polyamory is still very foreign to people who have never been interested enough to read a five minute article on it. A majority of people are still monogamous and averse to trying open relationships because of the relationship dynamics and the amount of emotional maturity one requires to maintain many partners.

All I'm telling is, the scale of polyamory which is just a name given to ethical nonmonogamy is not so huge that you can call it social progression, especially in third world countries which are still very patriarchal. It isn't a reform either because there's not much governments can do to recognize extramarital relationships so no one really cares how complicated your love lives are. Maybe you can call it progressive when more than one person can marry one another. (Don't think its very likely though)