Where is this new system for leavers

There needs to be huge bans for so many left games. I had a ranked game where the top lane fed so hard the other top was 6 lvl ahead of our mid. When I get out of game i check their last game history 8 left games in the last 10. How is this account still active? Why not ban this person form LOL they bring nothing but hate.

And if you dont want to ban them from the game altogether never let them play ranked on that account.