Support for MaxExtent is on our backlog, but not available at this time.
You could use the NavigationChanged event which is triggered after a navigation has completed, and then "snap back" to the extent you want to be in.
The next update is rather unlikely at this point. The main limitation is that this isn't really part of the ArcGIS System, so need to get it sync'ed up between all products (ArcGIS Pro, JS API etc)
Is there any release milestone for this issue? When I use the MapViewViewpointChanged or NavigationChanged event, it is hard to make it stable and robust when use zoom, rotate and moving. The MaximumExtent property in the previous main version (10.2.7) is really helpful for us.