It's against American roundabouts. Almost all the ones near where I live are too small (having seen them utilized effectively I Europe, ours are 25% of the size they should be) and/or are two lanes with particular turning rules that are only painted on the ground, force lane transitions, and are covered in snow during the winter meaning people who know what the ground says will be cursing the people that don't (and vice-versa).
They really did take the worst features of each type of traffic flow and merge them into an abomination.