One more thing - I don't think I've exploited "a bug" too. Some misclarification in the rules - maybe, but it's just the reason to update the rules a bit.
Not necessarily by forbidding to play with same person during a season - for less popular game it might be a crucial hit. But a further XP reward reduction is a possible way to discourage wasting time for those who are not interested in the game itself but in the easy ELO boost.
Another way is similar to that Swiss system: once in the top 20 you can only play with those in top 30, in top 10 - with top 20s only etc. Probably not so easy to implement, but this way you'll have to start earlier in order to climb up, and those who lose won't be able to help before beating some more loosers, which would take too much of an effort even for multiple-accounters.
Not necessarily by forbidding to play with same person during a season - for less popular game it might be a crucial hit. But a further XP reward reduction is a possible way to discourage wasting time for those who are not interested in the game itself but in the easy ELO boost.
Another way is similar to that Swiss system: once in the top 20 you can only play with those in top 30, in top 10 - with top 20s only etc. Probably not so easy to implement, but this way you'll have to start earlier in order to climb up, and those who lose won't be able to help before beating some more loosers, which would take too much of an effort even for multiple-accounters.


