Because it's weaker. Reborn the frog is only beneficial for Greybough, since this combination is most afraid of hitting when there is no taunt, hitting the Rivendare at the beginning of the fight guarantees a loss. Therefore, it is most important that the opponent always strikes a taunt, and the rebirth of a frog is an extra hit when a taunt is not called, an extra opportunity to ruin the combo. Much more important is the reborn bird and rat 32, and the toad is not reborn even if there is a possibility.
So only 2 golden 3-7. And one barren. That will spawn omegas. Without barren. Most of the birds will die but with a prock with a golden barren. What is left then?
One golden Windfury and he has a 50 percent chance of losing. Even a non-golden windfury can easily win. Splash with windfury will almost certainly destroy this board with one card.