Riot for the last time why am I getting new people in my games.

I'm about sick and tired of this, legit going make me blow a cork, yet again, riot i been playing for 10 years and I got someone that was brand new in my game, does MMR not apply? This kid didn't know the champ had no clue how to play him or at all, fed his butt off like no tomorrow, please just stop. Fix it.