That is not really a great argument. Pogba being 6th choice had less to do with his talent and more to do with SAF not willing to bow down to his demands. If we start using such examples, all youth players who moved at young ages from major academies and who had a very good career will be thanking their agents. Like Fabregas, Pique just two name two. Point is sometimes circumstances are like this.
As for Pogba, Juve wouldn't have cared two hoots about Raiola if Pogba was not the talent that he is. Hence it has nothing to do with Raiola. Unfortunately in this day and age, agents have all the power over a player and we have such situations arising more often than not. Agents like Raiola and Mendes should be banned from football.