I suspect lack of need for rollers is a primary feature. Conceptually, to me, the new interior bits serve as a sort of individual tooth holder that is free to

I suspect lack of need for rollers is a primary feature. Conceptually, to me, the new interior bits serve as a sort of individual tooth holder that is free to rotate with the tooth as the tooth orbits the axle. So there's not much friction at the tooth:holder junction as the sprocket turns. That friction is now occurring at the narrower intersection of a hinged tooth holder and chain link. Being a narrower hinge joint, just the length of a chain link's thickness, it has less surface area for friction, and less room for debris ingress etc. Conventional chains rotate a pin across the sprocket's thickness, and AIUI use a roller to try keep debris out of and lubricant within that interface to reduce friction. This contraption takes it a step further. You can actually envision the tooth holder as analogous to the roller in a conventional chain, just with less surface area at the twisting intersection. They've obsoleted the conventional roller.