I just started playing Final Fantasy VII for the first time. Unlike many of the earlier games, it seems to me that most of the characters are interchangable in terms of skills. Since you just use materia to do stuff, there's no reason why you couldn't pick three characters at random, say, Cloud, Tifa, and Barret, equip them will all the best materia, and then completely ignore leveling up the other characters. Am I wrong in this respect?