Sorry, it wasn't your experience I was trying to highlight, but just a general assumption that we all seem to make. Let me try to depersonalize this, and reframe my question as follows:
Let's say my measured average power output is 170 Watts for a given ride on my conventional bike.
If I do the same ride on an ebike, and can maintain a measured power output of 170 Watts, presumably I am getting approximately the same workout (but maybe I am going significantly faster, or can go twice the distance in the same amount of time).
I realize this isn't how people typically use e-bikes, but it suggests that they could be used by healthy/non-injured people as a viable form of cross-training.
In other words, does it really matter, from the point of view of exercise, if there is an assist motor present, as long as you maintain your power output rather than slack off?