Leavers in Ranked

There must be some sort of system that can be put in place to tackle this, how can it be that I am demoted to a lower league because of playing three 4 v 5 games in a row, one of which I played support, the adc came to lane, died once and left the game, not even 2 minutes into the game, this means I cannot remake and I cannot leave the game until everyone on my team agrees to forfeit, which can only happen after 15 minutes into the game, yet, I still lose LP and still get demoted. is there nothing riot can do about this?
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