It's partly accurate. The key is to look at the direction of thrust and then put the sharp edge away from the part that will push against it. The idea is that the clip will not be pushed out of place. If the rounded edge was taking the thrust, it might be displaced by the sideways force.
With an external clip on say a sprocket, there is no way the sprocket could be pushed into the transmission, so the sharp edge on the outside minimizes the possibility of the sprocket pushing its way off the shaft
With an external clip on say a sprocket, there is no way the sprocket could be pushed into the transmission, so the sharp edge on the outside minimizes the possibility of the sprocket pushing its way off the shaft