Why do e-bikes have tiny chainsets?

[Racingt]

Provided, of course, that the chainwheel moves at the same speed as the crank. I believe what was inferred by the previous poster was that it didn’t, hence you needed to calculate a higher chainwheel number of teeth.
Personally, I want to see that theory proven before I fully accept it. Not saying it’s wrong, simply that I still don’t understand why eMTBs have such small chainwheels.