Earlier quoted context omitted.
> The present is, however, Slack. Actually, in terms of number of users, the present is MS Teams. Both companies release their numbers and it's not even close.
Not surprised there. Plenty of companies already in bed with Microsoft. This allows them to maintain a "familiar" setup to everything else they have. Still feel like competitors can do better though. Microsoft Teams looks nice but people still have issues with it. I only used it long enough to not see those issues.
What's important is that when you log into your email account, you're logging into Teams, Planner, etc. I recently started using Planner, as awful as it is (seriously, you can't even drag cards!) because I can't expect others to adopt a new tool.