Why is the game still broken?

It is not that easy, just because creating a moderation team either gives too much power to someone else to ban IP indiscriminately or just requires extra money.

The easiest way around is exposed in my thread Game drop ban does not solves or improves game experience completely If you avoid people to purposefully loose elo fast by implementing alternatives to early game drop that dont modify anyone elo when the match is made unfair by one dropper either it is purposeful or not, you can avoid the sandbagging in the first place.