I disagree with silux.
First, you are claiming "if it can be countered, than it is balanced"
I personally do not agree with this statement. If we make an overpowered card that, when put into a deck, defeats all other decks and the make a card that can counter it, then all decks would either use that overpowered or the card that counters it. This contradicts the "balanced" idea you outlined, where each player has 3 choices and an equal chance to win with each choice assuming the opponent chooses a choice randomly, for a skewed interpretation where rock can beat scissors, knives, forks, and peace signs and paper can beat rock.
Second, there are three ways to counter strategies:
- prevention
- mitigation
- reversal
prevention is obvious. set up the environment so that the opponent cannot set up the targeted strategy.
mitigation is also obvious. after your opponent has set up the targeted strategy, you try to destroy the environment/strategy the opponent has set up so that the opponent cannot continue to use the targeted strategy.
reversal needs a bit more explanation. after the opponent has set up the targeted strategy, you have to set up an environment where, if the opponent continues to use the targeted strategy, it will backfire or you will win.
I'd prefer much more the superdeck to be countered by having more counter cards or counter strategies, because the deck became so powerful not because of the cards but because there where few or no counters.
now, let's try to counter the hypothetical super-deck of rushes that get out 33+ damage on the first turn
prevention - does not work, because rushes will always be faster (unless you have cards that activate from the hand, without the need to wait to get quanta from pillars or such)
mitigation - unless you can completely wipe their field within two turns and then set up prevention, you're screwed. and with the ability to wipe their field comes the ability to pwn EVERY creature-based deck, not just the hypothetical super-deck.
reversal - sacrifice. however, everyone thinks sacrifice is OP. so what do you want us to do, make a way to counter sacrifice? as you've seen from this example, prevention and mitigation are too slow without making something else to yell OP over. heck, even reversal may cause something OP to yell over.
we know that the current meta-game is balanced. the introduction of game-breaking cards shifts the meta-game by forcing changes in players' card choices. whether the resulting meta-game is more inclusive or less inclusive is completely independent on how the meta-game has shifted. however, note that shifts cause the meta-game to become less stable (because the current, balanced meta-game is tried and tested). in addition, players view large shifts in the meta-game as bad.
Conclusion: game-breaking cards can only be countered by game-breaking cards. The introduction of these cards causes shifts in the meta-game that will result in a game that some players may view as a completely different game.