Quasar and red nova are nowhere near being the most broken cards in the game.
Yes they are both very good cards, and yes they are hard to get over, but if you know what to do you shouldnt have a problem, plus the fact that they arent very splashable.
1 = not hard to get over, 2 = very difficult but still possible 3 = you need a miracle.
But like I said, 1 of either is somewhat versatile, but niether are splashable, meaning that if you compare them to other cards who's effects aren't as good but are still good and the card is extrememly splashable it is more broken.
Like brionac before he was banned, quasar or red nova trumped him 1v1, but with as splashable as brionac was he was more broken.
Just because a card scrwes you over or you dont like going against it doesnt mean that is is super broken.