The thing is that you don't actually NEED a 0-CS support at low ELO which most people play at. The fact is that most AD carries in average ELO games will miss shitloads of last hits, enough that having someone else in the lane to pick up the scraps will probably work just fine. Not to mention most people who would play support at that ELO wouldn't have the competency to make split second decisions in teamfights that would help the team win, as opposed to them just playing Tryndamere and right clicking someone.