Game balance is actually something different than Rules balance, where the former is the act of balancing the game as it is being played at an actual game table, versus the latter which balances the mechanical elements used in this game and written on paper.
Some amount of Rules balance in a game is a commandable goal. It ensures that players have choices to play the characters they want, and yet do not get a mechanical upper hand that would rob other players from their own thunder. That's all fine and good.
Game balance does not solely rely on Rules balance to happen, though. (...)
If I may bounce on my own post, here, I will also point out that advice to DMs and players not only explaining why this or that mechanical aspect of the game's design matters, but also
how it matters, in which particular game play assumption and particular situation as it relates to other elements of the game's design, is absolutely critical for the users of the game to make actual
game balance happen in play.
It seems to me that in too many game designs, the rules, and the rules only, are thought to provide the frame through which enjoyable game play can happen. This is a dangerous fallacy, in my opinion.
RPG rules come in play through one medium only: not the rules book, not what the game designer thought the rules' role in game play ought to be, and certainly not in some sort of theoretical vacuum where "the average group would do this or that", but through the particular users of the game, the specific game group, as they actually play it. Therefore, making these users understand what the game designer had in mind, and providing them with the tools to understand the logic that sustains the game's design, is extremely important for them to be able to handle the system properly and extrapolate on its tenets as they come to "own" it through play.
Just as the rules themselves cannot make game balance happen, advice themselves probably won't either. There's a careful balancing act to be played here by the game designer. How well the audience of the game is identified, and what is thought to bring the most pleasure to each particular game table, ought to be one of the major tools to balance these two particular aspects of the design.