I'm using Teams in a 10,000 person company with employees and external collaborators. Its our primary chat tool, and its used regularly for presentation broadcasts of over 250 people. Is this Enterprise enough?
How do you get notifications from all tenants at the same time? How do you even check the other tenants when you are in a Teams meeting? I mean, the client disconnects from the meeting if you try to view other tenants. How can you see which channels across five tenants have new messages?
If you are a small company and use Teams internally. Fine, but it simply does not work in an enterprise environments.