So the argument is that it isn't bad when a small percentage of cyclists hit 25 - 30 mph, but when all of them are able to that is where the issue is.
My personal feeling, however, is that especially the models that are pedal assist (where you put some effort into it, and it multiples your effort) is a good way to get otherwise low-fitness people to bike ride more. The more cyclists, the more push for bicycle friendly infrastructure. And people still get exercise on them, more so than in a car.
But regardless of powered vs unpowered, anyone that rides a bicycle fast by pedestrians and dogs is doing it wrong. On an ebike, it should be no effort to slow down to 5 - 8 mph, then speed back up after passing someone.