I have one. When you move from your assigned seat, you don’t get to be an asshole to the people in front of you.
Ex. A: On a cross-Atlantic flight I was lucky enough to have no one behind me such as to be able to recline with impunity. 12-year old from somewhere else on the plane decided the empty row behind me was…

I can tell you who would do that, at least in one case. Boarding a shuttle flight from Spokane to Seattle (2 seats per side) I had the misfortune to be seated on the aisle next to a woman so obese she could not sit w/ the arm rest down. I had half my seat to sit in and only the outside armrest kept me from falling…