Marriage was already comprehensively deconstructed by heterosexuals, long before the homosexuals swarmed in to claim its parts and bits. Through civil marriage, easy divorce/remarriage, and contraception, heteros redefined marriage from being a Natural Law-anchored, fertile exclusive lifelong union, to being a construct of positive "say-so" law, sequentially multipartnered, and sterile.
Marriage --- as obviously defined in all of human history across centuries, continents, and civilizations --- makes sense only as a setting for procreative sex which then defines two-and-only-two people, the male and the female, as the responsible parents. People of random genders rubbing non-procreative body parts together don't require solemn durable societal recognitions, responsibilities or covenants. In such case, there is no need to specify one, two, three, any number of people, and it doesn't matter whether the non-procreative parts are elbows, anuses, noses, knees or reproductively disabled genitals.
Who queered marriage? Heterosexuals. They "redefined" it. It's inevitable that the various kinds of queers would now claim the mutated thing as their own.
I’m starting to think we just drop out of these debates. Or at least make them tell you what “advantages” they want. If they want to be able to visit in hospitals or get a tax break, say “ok, go for it”.
When they want a priest or pastor or rabbi to preside, let the debate begin.