Intelligent Design

I can't see any problem with no rings changing to one. Imagine a rod rotating in a smooth sleeve bearing - it will be effective, but it will tend to wear and go out-of-true. So there will be an evolutionary pressure to build up reinforcing rings at the ends of the tube, and a tendency for the centre of the tube (which is unused) to disappear. These rings will then tend to operate a little bit like ball-races. This is a credible sequence.