Random auto fill in low tier play

Why? In low tier play, people really really specialize in maybe two roles if you are lucky... I have gotten ranked games where I am playing adc and have a support who has never played support. What kind of cruel troll move is that? What is the point? Riot, please don't F*ck up people's games by placing people in roles they cant play... My que times have not gotten better and all I am getting out of this are unnecessary losses.