As far as I know, MMPK are authored in ArcGIS Pro only.
That is what I seem to understand but I have not found any ESRI documentation that confirms this. I will need that documentation for my managers. Thank you!
The help files are useful for confirmation, generally, if it is a tool, and it doesn't exist in ArcMap but it does in Pro, then Pro has the functionality and vica versa.
Create Mobile Map Package—Data Management toolbox Pro 1.3.x
An overview of the Package toolset—Help | ArcGIS for Desktop ArcMap 10.4.1