Would you get more leavening if you used both whipped egg whites and egg yolks and folded them into a batter (pancake batter,for example)compared to using whipped egg whites only, and would it make a noticeable difference? If yes, then why is it more common to use just the whites?
Whipping egg whites is usually done to make a batter lighter and fluffier. In such a case, adding in egg yolks will likely make the batter denser and less fluffy.
On the other hand, if the recipe has substituted egg white for egg in order to make a recipe healthier by reducing fat content, you can revert to using whole eggs (1 for every 2 egg whites). The texture will still be different, but that might be what you want.