Because tax benefits! I’m kidding, sort of.
For me, the only reason is for the benefits. I just don’t see the point in marriage otherwise, but that’s just me. There are many other reasons to get married though.
For starters, unions (marriage, handfasting, etc) are often super important thing in many different religions, and there are plenty of poly people that are religious.
Many poly relationships start off monogamous. These people are sometimes already married, so why would you change that? (This is the situation that I’m in)
There are indeed the tax benefits, along with other things. For example, R and I got married so that R could adopt our twins.
Then, there are the already poly relationships that decide they all want to marry each other. They go through the marriage, but unfortunately, you can’t legally marry more than one person, so there’s no legality to it, but the custom is important to many, many people.
Beyond some killer tax stuff, and the ability for R to have decision making capabilities with our children that he has no legal relation to, I couldn’t care less about marriage.
I can’t even say that I really understand the obsession over it, but I do know it’s important to many people, and poly relationships don’t change that in the slightest.
Thank you for reading and have a beautiful day sunshines!