Whilst this is literally true, the myth is in the way it is used to suggest that there is an issue that does not actually exist, for three reasons.
First, it is a straw man; nobody is suggesting a ban on all motor vehicles. Of course motor vehicles are needed for some purposes. So what? We can still use them when needed.
Second, a very large number of deliveries that are currently made by vans could be made by cargo cycles (including electrically assisted ones). In London, Pedal Me are carrying many people and some rather large deliveries (Twitter thread) using them. In fact there are more and more businessess using cycles, as shown by this Twitter account.
Third, one of the big problems for deliveries is congestion caused by people in cars making short journeys that could be walked or cycled. So this is actually an argument for freeing up road space by enabling more efficient travel modes (walking and cycling); I’m glad you agree!