well there is no way to reduce/eliminate run selling short of saying its not allowed and banning people for it, or keeping their current system which hurts any group of friends/FC members who doesn't hit their magical 8 number. It really is about picking the lesser of two evils, and I for one would rather let people run coil and other such content with friends then force them to sit out because their group is already full... which is exactly what leads them to buying runs through content... or you know, just sucking at the game.