Matching toxic players together
I assume there is already a hidden "toxicity" variable associated with a user's account based on the reports that user has received. It would make sense that the punishments would be handed off based on such a score.
But what if such a score is used comparably to how MMR is used in that it preferentially groups together players with similar scores. This would not only create a separation between toxic and normal teams but create an incentive to straighen your act if you want to be matched with more game-minded players in the future.
Something like this may already be implemented with the honor system, but I'm not aware if the above idea has been.