Weight and velocity are also important (potential energy which could cause harm) but acceleration is the right way to sort things into lanes, there can also be an energy constraint for the lane but acceleration is about being able to anticipate the behavior of something so that you can avoid the accident in the first place.
Electric bikes can accelerate fast and the user will also not care as much about stopping (and losing hard won inertia) this could invalidate some expectation and cause an accident.
Finding a good compromise (such as [1]) I think is a better idea. Lowering car speeds such that we can mix is a good one, as well as the introduction of speed limits on cycling paths [2], which would force certain bikes to slow down.
[1] https://gratistheorie.nl/wp-content/uploads/2018/06/opgeblaz... [2] https://www.fietsersbond.nl/nieuws/een-maximum-snelheid-op-h...
As a cyclist, I don't believe this claim for a second.
When a car starts moving at the same time as me, it's faster than me from the start. Which makes sense, it has more horse power per unit mass.
Often I do start moving first, because I think I'm less likely to get right hooked if I do so. But that's a result of paying attention and having my for on the "accelerator" waiting to go. (Also maybe a tiny bit of lag for a car to get into gear, but that's not substantial).
I do agree that a good electric car may start faster than a cyclist, however.
This is not ideal, as the (fast) electric bike is new, also in NL, and people will misanticipate them (which I've experienced first hand). You're right, mixing speeds is a bad idea. This will improve with better infra (wider cycling paths, bike highways) and getting used to this new vehicle. On the other hand, the problem is similar to the scooter, which also doesn't fit the car or bike class, so perhaps with time a new type of lane must be invented. Some cities/political parties in NL are thinking of lowering the car speed limit from 50 to 30 (in urban area), which will facilitate mixing in scooters and electric bikes with car traffic.
Another important fact is liability: heavier vehicles are more liable (weight makes responsible). So in any accident between, say, car and electric bike, the car will be at fault by default, unless there is proof to the contrary. This leads to more cautious driving.