But the answer is actually within those lines. One of them exerts a lot of effort in using their mouth and tongue while the other would just lie down there while they get their dicks or butts stimulated by their partners.
You might think that most positions tend to favor only one side of the party, just like blowjobs and rimming. Now, since romantic relationships are also about sex, the question is - what sex position is all about giving and taking? If you think about it, the answer is actually not that hard to find. It's those give-and-take relationships that work the best because this is what relationships are about in the first place. You also need to be there when your partner needs to get his freak on, and so does he for you. It's your responsibility as well as your partner to cover each other's backs and mind that this is not exclusive to just house chores or paying the bills. It's not that you need to keep score of who has done more for the other and crown whoever is leading that race, but it is important that you return the good deed as you and your partner are the only ones who would do those things for each other especially in times of need. In a relationship, it is important to reciprocate every positive thing that your partner does for you.