It means assigning antiquated and fairly obsolete notions of gender onto sexual roles. For example, sexual roles that simplify into concepts of male and female, masculine and feminine, dominant and submissive, top and bottom, etc. In other words, borrriiiinnnggg.
Personally, I find it far more interesting, engaging and liberating when the line between sexual roles becomes obscured, or even done away with completely. I also find that porn that perpetuates this mythical dichotomy between roles is fairly oppressive, especially in heterosexual porn. Just think of all those disgusting humiliation videos; they feed off of that dynamic.
I know what you are saying, I have been with my partner for a year and we don't have anal sex. Neither of us are top nor bottom, we do different things when we have sex, we involve kink, and express ourselves sexually in all kinds of ways. I know all about the gray area and the freedom and equality it brings...but we are not talking about real life here. For a minute lets all stop being so serious here. I intended for this thread to be about porn, NOT real life obscurities and complexities.