>> Your users live in Teams.

> No, I assure you, we do not

This absolutism is tiring. I can assure you there are plenty of companies who use teams as their sole messaging platform. My company uses slack, teams, and zoom. Which one you use the most depends on the person or the team they are on. (Although zoom is being phased out to the chagrin of some folks).

Teams isn't without it's issues, it's annoyingly slow, and startup takes so long I have missed a meeting or two because of it. But, the conferencing experience is pretty decent, and I think you're just being contrarian for the sake of it.