See, "knowing your character" doesn't seem like "optimizing" to me. I mean, maybe "use your character better, tactically" is close, or at least pointing in the direction of a kind of optimizing. Just knowing the rules that apply to your character, though--that just seems like knowing how to play the game; maybe there are players for whom the rules of the game aren't really important, and maybe there are tables made up of those players, but game/fiction preferences again don't seem all that optimization-centered to me.