Riot Why is there No ingame Kick system

Time and Time again I have played 40 minute long games where one player goes off the deep end and intentionally feeds for god only knows what reason and then 4 players get stuck in a miserable game that is no where near fun or coming back to play. Why are we not aloud to kick a player? there are so many 4v5's I've won where we simply toughed it out I would rather play a 4v5 with a feeding or toxic player