I have been with the game a long time -- look at my join date. I don't think what Kmnh states is actually the case for the vast majority of players. I do think it is true for a certain portion of the player population. But, for the typical player I don't think this is what you are going to run into.
My personal experience is that there are far more players who are only partially self sufficient and the vast majority of players are almost completely dependent on others -- whether that is other players or hirelings.
IMO the original poster has a laudable idea. I will only kibitz on the classes being suggested to say that any spell casting class -- divine, arcane or specialist -- can be built for such a role.