See? I told you I hadn't played the game yet.
Towards the end of the game you get people frantically playing merchant ships to avoid negative points. These ships are easy pickings should the game last longer than expected, which can happen should the player or team with the smallest hand choose to draw instead of play (increasing their hand size and thus the game, which requires an exhausted draw deck and an empty hand).
Mostly, though, merchants dumped at the end remain as incomplete battles and thus are rewarded to no one.