Right now, you'll get elected if all your population is in one region, so you tell the minority groups not to try to settle in various places but to all go to Saint-Léonard, Outremont, or wherever, and then they will be able to influence politics.
If you want to create ghettos, it's a great system. Otherwise, you can tell people that it doesn't matter where they live because they'll have the chance to elect the person they choose.