If that's Skype For Business, you've got somebody who set it up in a really bizarre way. It's such a clusterfuck of policies and settings that I'm not sure just where that would be set or what powershell gods you have to worship to straighten it out, but that's not the default out-of-the-box behavior.
The client is trash, though. Never understood why you can't run multiple accounts, or at least multiple instances without massive hoop-jumping. Aside from some reskins, it's the same as the Lync 2013 client, and that wasn't much of a change on the 2010, or even 2007 client.
As a Linux guy, I tried to setup Office365 OneDrive for the technologically illiterate side of the office, because they get 1TB. Set it up on a 7 computer, an 8.1, and a 10. Used the registry key to activate business accounts mode. Made an Office356 Group to have a shared directory. Looked at every alt menu and right click menu for shared directory options. Nobody could see anybody else's content no matter what I did. Then I spent 10 minutes setting up a NAS on a random PC and mounting it on all the other computers, used OneDrive on that PC and was good to go. I think I'll never use one drive, I've never had a sharing issue with any other cloud drive provider.
The client is trash, though. Never understood why you can't run multiple accounts, or at least multiple instances without massive hoop-jumping. Aside from some reskins, it's the same as the Lync 2013 client, and that wasn't much of a change on the 2010, or even 2007 client.