Congestion is a mutually exclusive issue - obviously a 300mph Bugatti can only go as fast as the traffic flow in LA rush hour traffic. You seem to be suggesting that just because some cities have "bike congestion" we should set the assist limits at that lowest possible speed. Sorry but that makes no sense to me because the conditions are controlling the speed bikes can safety go. I have heard this argument many times and it's just not a relevant response in the topic of best regulation performance.having spent a lot of time in the netherlands, i’m not sure a faster ebike is really needed, transportation is predominantly bike not car, bike traffic is a real thing in city centers and there’s a lot of bike congestion so there’s not really much opportunity to go a lot faster than the speed everyone else is going. helmets are also frowned upon/not used so very fast speeds are probably less recommended.
Some riders will have longer commutes and access to road side bike lanes or other infrastructure that would allow safe higher speeds than what is possible in the Netherlands cities. When there is congestion they will just have to slow to what is allowed by the conditions or actual speed limits of the infrastructure being utilized.