Teams (and Slack etc.) have a terrible signal-to-noise ratio
Skype for Business is primarily a one-to-one instant messaging tool. When the little popup appears telling you there's a message, you know it's directed at you and is personally relevant.
Teams is a group chat tool, where you hear a cacophony of voices shouting over each other. It has all the problems of meeting rooms, only worse because it never ends. Meeting attendees are desperate to show off, so there's a lot of redundant noise. You have to sift through the entire conversation, even if only 5% is relevant to you. Just as you can spend your whole day in meetings if you're not careful, it's easy to spend hours on Slack or Teams channels, poring through other people's never-ending stream of consciousness.
I honestly can't understand how any of the Teams / Slack / Mattermost / etc. tools were ever considered to be a productive use of time.
Biting the hand that feeds IT
