The Rebels were fewer than the Primal Pantheon. They had always been fewer. However, they had never been weaker than the Primal Pantheon. The sole reason the Rebels never beat the Primal Pantheon were the Primal. They had been the Pantheon's safe haven whenever the Rebels attacked the Pantheon.
However, something changed two decades ago. The Primordial Curse, the strongest being supporting the Rebels, disappeared. The Primal Pantheon attacked the Rebels in the isolated dimension and sealed the place to block their enemies from fleeing and requesting reinforcement.
But that was something the Rebels never wanted to do. They knew the Primordial Curse wouldn't come for their help and that there was no one left in the weave to help them. Many gods and other powerful beings may spread through the weave, but most of them chose to retain their neutral stance.