>>82564856As the world grows away from morality, whether actual or institutional, we still retain the need to pressure people into certain behaviors. Right now, peer pressure and disgust are the strongest. So instead of saying "sex with this or that is wrong because that's not what our creator intended for our genitals" it's just "that's gross" or "nobody does that"
until society decides it's okay, then it's "nobody feels that way anymore" if you don't immediately 180 and decry everyone who ever felt otherwise.