Now this isn't a new concept exactly, Shaft-Driven bicycles have been experimented with since the bicycle was invented.

Crucially though, they were all singlespeed up until very recently with advanced gearboxes, and even then, they never took hold. They're more expensive to manufacture, it's all propietary stuff so good luck servicing it and the efficiency losses are way, way above what even a dirty chain gets you.

Enter ceramicspeed re-inventing the wheel, basically. Admittedly, their target audience cares little about propietary or price, so they got that down. So they invented the shaft driven cassette drivetrain.

Now, you might look at this and think: "Well, what if we introduce literally any dirt to that thing" and the answer is don't think about it.