Just set this up real fast as a quick backup, since we already use Gmail and everybody is already in it. Having a non-AWS hosted solution seems important to have a Slack backup for me, as well. Oh hey would you look at that, they support webhooks too...
We switched from Slack to Teams for various reasons about two years ago. I'm still mad about it. Teams blows for chat. The video meetings are fine though.
The MS Teams UX is pretty painful, especially for infrequent, communication-heavy users. Not painful enough to outright prevent work, but clearly more painful than the repercussions of missing a few hours of work.
This seems at best a funny tweet. They're both just tools and frankly terrible in terms of "getting work done". This seems like a great time to go heads down on a deep task and if you really need to contact someone send an email or even phone them.