Earlier this year I predicted that many IT pros would opt to do MS-300 purely because of Teams. I also predicted that Teams would eventually go on to have an exam all of its very own. And whilst, admittedly, it wasn't MS-400 we now have MS-700 - Managing Microsoft Teams as announced at Microsoft Ignite 2019. In passing MS-700, the delegate goes on to achieve the new role of Teams Administrator Associate.
I think it's fair to say that a lot of people will do this exam because of Microsoft Teams. Teams is, after all, the fastest growing app in Microsoft history. At the time of writing there are over 500,000 organisations using it. 91% of the Fortune 500. At the time of writing (May 2019) there has been lots of functionality introduced this year or coming in the next few months. It's hard to keep up - even for those administering it every day. Private Teams, Information Barriers, Busy on Busy, Round Robin, App Deployment Policies, Supervision.