It's a shame we live in such a hateful, bigoted society.
I don't think hateful and bigoted are the best words to describe this society - don't get me wrong, I acknowledge there are many subcultures that are. I think a more realistic view of society as a whole ties in to change-aversion and ignorance.
LGBT marriage equality gained acceptance by becoming familiar. People without hate or bigotry just didn't understand it and so didn't support it. By coming out of the closet, being seen, and especially becoming more visible in media, ignorant and change-averse society became less ignorant and less change-averse.
I'm probably overestimating the timeline for poly acceptance, because LGBT acceptance WILL open doors here. Maybe a ten year period is more realistic provided there is exposure to the group, especially in the media in a positive light.
"Society" does not exist without shared beliefs, and those who would adhere to so gross a negative generalization can/do not reside within mine.