Is it at all possible for a unified view in Outlook online?

Am I missing the ability to have a unified view for Outlook online? On my Mac and iPhone, I can easily select All Accounts to see my account and the Shared Mailboxes and other accounts I have access to. For Outlook online (and Windows, if memory serves), this is not a thing.  

Users are struggling to grasp the concept of checking both their account and their Shared Mailboxes and reporting that they're missing messages. I don't see a way to solve this other than telling them to check every mailbox every time the look at Outlook online. Unless I'm missing an obvious step, this seems like a gigantic bug that needs to be squashed. I mean, we're talking about Outlook.