The lowest common denominator in the goal.
100% truthiness here.
Outcome Based Education was the first strike.
No Child Left Behind was the second.
Common Core is the third.
OBE slowed the pace of material, dictating that new material cannot be presented to a class until a certain saturation rate had been achieved with grasp of the current material.
NCLB made it far more difficult to force a child to repeat a grade. And it bored the gifted kids to tears, and basically manufactured the "ADD" plague from thin air.
CC takes away diverse/multiple ways of teaching a concept, and forces presentation of that concept using techniques tailored to the worst performers.