Those rules are about delineation between scooters and bicycles. The easiest way to think about it is this: Bicycles have performance limitations for safety and

Those rules are about delineation between scooters and bicycles. The easiest way to think about it is this: Bicycles have performance limitations for safety and licensing reasons, pedal assist with a speed limit has proven a convenient performance measure for a bicycle in a bunch of countries. Scooters have no such performance restrictions and as such require licensing, age limits, insurance and all that jazz. So TL;DR it's just a convenient demarcation between two classes of vehicle performance, that doesn't also limit human only powered bicycles or full scooters.