You might be able to make a (weak) case for indexed shifting of any type, including electronic shifting, being "digital" in that the shift positions, unlike friction shifting, are discrete points.

But there is nothing specifically "digital" about an e-bike.

Conflating e-bike and e-shifting is also a complete non-sequitur.

A friction-shifting non-ebike is not an analog bike, nor an acoustic bike. It is simply called a bicycle. The lack of popularity for a non-vintage/classic old bike is simply its lack of versatility with respect to tire clearance and other features that many riders now prefer.