This is another answer to a question no one was asking. They pop up every twenty years going back to the 1890's. They die out in a year or two.
Just like all things cycling related are magnified in an e-bike, so are bad ideas. An e-bike performs best when you spin with a smooth and even stroke. These are made to take advantage of mashing during that piece of your stroke where you are using the largest muscle group. They slack/loose chains and tear up drive trains as well. They are an all around bad idea