Probably it's easier to argue this on a small company, where the developers have a bigger impact. But I think in most companies, nobody asks the developers about these things. If the company is already invested in Office, then it's a no brainer to use Teams. It's free and supposedly does everything Slack does. It's well integrated with Outlook/Calendar, etc. When you already have a free solution it's very difficult to ask for a paid service with similar functionality. I don't like using Teams, but that's not a hill I'm willing to die on.

To be honest, the only complain I have about Teams is how resource hungry and unresponsive the application is. But I think it does (or should I say "attempts to do") some things better than Slack. I like the way Teams displays the chat threads as conversations instead of a long, narrow and claustrophobic column on the right, for example. But, again, nobody asks me :)

Now it's not only for devs.

Synergy!