This is a basic idea. I understand that HUB sites are really designed to be completely transparent. However, the reality of the world we live and work in is that there are data sets that cannot be public but still need to be shared with an intended audience. ESRI should allow users to create Hub sites that allow users to share proprietary data among a selected group of people without sharing the information publicly.
Point of clarification. I think this should be done through a service and not force the user to upload the data to AGOL as a HOSTED Feature Layer.