IF the gayest society did not recognize gay marriage why do you?

I just saw a question about gay marriage that seemed to assume that in the most gay of societies such a thing would be approved. IT NEVER WAS
“He [ Scalia ] asked attorney Mary Bonauto, who argued in favor of same-sex marriage, if it were true that homosexual
relationships but not marriages were sanctioned by those cultures.
“When she said yes, Scalia continued, ‘So their exclusion of same-sex marriage was not due to prejudice, right?’
Adding, unless she considered Plato prejudiced.