Depends what you mean by “CAD”. If you mean Revit, yes, that was the case, but we are about to release a Revit plug-in. Otherwise, Studio supports about 20 files natively, including the big ones like Catia, NX and Creo. There are reasons to use 3ds Max still to add modeling details or to make large changes to a scene, or to address tricky UV issues. It all depends on what you’re trying to achieve in Unreal Engine.