> one value in doing it plain is it's easy to fix and get parts anywhere

That's probably the main value. In the article it says he waited three days for a bike chain - I imagine it would have been even longer waiting for a belt. Belts also limit you to single-sprocket rear wheels since they don't work with derailers - hub gears can be reliable (see the legendary Rohloff hubs) but they're expensive and add another difficult-to-source part to the build in case something goes wrong.

There's even something of a cult myth in touring that steel frames are superior since they could be theoretically fixed by anyone with a welder. I'm not sure if I've ever heard of this in practice, though.