Know the difference between polygamy and polyamory. Polygamy isn't that uncommon but is often used to serve patriarchal hierarchies. Polyamory is much closer to "do whatever" (though that's not strictly true).

I'm trans and let me tell you so many of us are polyamorous. In my personal experience it has to do with spending so much time fighting against society to claim our identity that we end up questioning a lot of social norms. I think that more people than we realize could live very happily being poly, and if we had better poly representation more people would know how to approach it in a healthy way. But it doesn't serve the hierarchies we live under to let people love freely in that way, so it gets othered in media and by governments.

Also the "groups" you're talking about teaming up in are typically called polycules. There are a lot of forms they can take it is an umbrella term.

I think that as people are made more aware of the harm caused by some aspects of society we'll be better at questioning things like monogamy as a whole. It isn't an overnight thing. Also, often even in the poly community it is considered an unstable way to raise children (I don't agree with this but it is a common enough sentiment). I don't think polyamory will overtake monogamy certainly not any time in my life but I hope it becomes more common.