Equality of what? Equality of ability to exercise the right to marry and have a family (eg as noted in the declaration of human rights). As for polygamy, that'

Equality of what? Equality of ability to exercise the right to marry and have a family (eg as noted in the declaration of human rights). As for polygamy, that's not quite got the same status, no. And the UN Human Rights ctte has called for it to be outlawed, as it already is in many US states, because it violates the dignity of women in particular. So I think that is vastly more complicated and legally murky area than two-party adult marriage. Regardless, I fail to see how the extended riff on edge cases and the revelation that marriage isn't a physical or biological construct has anything at all to do with its trendiness.