A couple of players in the chat were talking about how we bought out AI's (dropped players) first out of courtesy, so we decide to try the option, part out of wanting to enforce that and part out of just wanting to see how it would effect the game.
Problem is, there were no AI players at the time (at start till about the end of the game). So players could only buy offensively, and get defensive stock by buying out others who bought their stock.
Noticed in an mp game earlier that when this option is selected some players could not buy their own stock. I don't know if it matters that there were only human players at the start. 2 players noted this problem.