I have not found a way in ArcGIS OnLine Web Mapping Applications nor Web Maps to limit how far users can zoom in or out. It is possible if there is a cached base map, but not otherwise. Setting scale dependencies and limits on REST services and layers does not negate this need. That will stop the layers from being displayed, but still allow scales that may cause users confusion, frustrations, and problems. Setting a default scale and extent will also fail to address this. This function was possible in an older ESRI platform, ArcGIS for Flex, by specifying LODs.
Does anyone know if this is possible?
Example of my user's problems: Have a global map showing total population by country. The current setup allows a user to zoom in very tight (like to 1:1,147) of automatically zooms to such a scale after searching for a point location. At that scale the user will most likely be deep inside one country's polygon requiring them to have to pan and zoom back out many times to see another country to compare to.