1.) It applies only to heterosexual couples.

2) It assumes all people are binary

3.)It assumes gender isn't able to be changed.

4.)It assumes no one is ACE or Poly

5.)It's antiquated and based on a social system that people had to actively rebel against

6.) It assumes marriage and children are everyone's goal

7.) It thrives because of notions of superiority vs inferiority, ego feeding, concrete thought and false dilemmas.

It's just not the case as society has pointed out time and again.