If they can gain the divine ability of another race, why not take the divine ability that will allow them to take the divine ability of others? They did and they realized that the divine ability of another Shapiro doesn't take up their single slot, instead, it adds to it. At the end of the day, the perfect divine ability to increase their potential is the divine ability of another Shapiro. It solved their problems and more.
This obvious solution came with a lot of problems too. It doesn't work for transcendents. The awakening of their divine ability a second time makes it impossible to increase the amount of divine abilities they can take. That means they had to increase their potential and the amount of divine abilities they could take before they became transcendents. That is how the blood crucible was born.
