Here's the thing though: You can tell someone that if they don't want to break the game, then simply stay away from anything that's too OP, but I don't think a player should ever have to make that choice in the first place. I think any instance where a player has to either deprive themselves of an element of the game, or to trivialize content is an instance where the game designers have done something wrong. In an ideal game, a player should always be able to make use of any the game's mechanics and optimize their characters while always being reasonably challenged, and while it may not be possible to achieve that 100% of the time, I think it's for that reason that balance is very important even in single player games.