Why does any one has to go through a 4 man premade?

I swear Riot path of premade is stupid, just had a 4 man dynamic duo which 1 idiot did not lock in Darius to show he was going to pick it so i ban it then ban my champion. Next best part is trying to carry the idiots but 1 of them D.C... WHO DO I GET PUNISH FOR ELO IF A PERSON WHO IS DYNAMIC DUO WITH 4 PEOPLE D.C?