After the installation and configuration of MIM 2016 following this link, I noticed that no users can be synced from AD to SharePoint User Profile store. The Synchronization Service Manager shows the screenshot below.
All users fall into "Connectors without Flow Updates", and got filtered during syncing.
To fix that is easy: add a join rule for "user"("Data Source Object Type").
I am quite surprised that this is not added to the Step By Step Installation User Guide.