Only in the very short term. People have move goods, or the city goes hungry. They have to get to their jobs, or essential services are not provided.
Yeah, I understand. First I thought: what about bikes and public transport only? Then I thought: there has to be trucks too, to move stuff. Then cars. So, back to the same.
But I guess a traffic ban is better than some have suggested: nuke it, bulldoze it, and start over again :-)