That's silly. They are collectively centering on something (in this case, an idea), and they surround the center point.
The verb to center implies a linear directionality from possibly more than one point due to an implied radial origin. We add "on" to emphasize this action. But to "center around"... that's messy. It blows the implication of linearity to bits.
The verb to center implies a linear directionality from possibly more than one point due to an implied radial origin. We add "on" to emphasize this action. But to "center around"... that's messy. It blows the implication of linearity to bits.