In addition to other comments, from an academic perspective, Teams was at least in the pandemic era
horrible for meetings and conferences with people from many different institutions: account handling across institutions/installations was atrocious. It seems like it simply was not designed for that use, but then seems to have been heavily marketed to university administrations. For the most part, it seemed very difficult to use an email for login on Teams run by one institution if it had been used for Office365
at any other institution anywhere.
Especially for things hosted by UK universities where it seems like everyone was forced to use Teams, I remember seeing absurd instructions for conference and workshop registrations, like "Please give us an personal email address to use as your login that is not your institutional email address, and that you have never used for any Teams-based conference in the past."
Then actually trying to run conferences on Teams always seemed to work horribly by comparison to other systems. One workshop on Teams I went to (with ~60 people if I recall), for example, couldn't figure out the access controls for screen sharing, and some users would accidentally share their desktops, which they then had trouble stopping. For larger conferences (eg, 100-400 people at a talk), I went to several where, since it seemed that they were already frustrated by Teams but seemed pushed into using it by their university administrations, they would use Teams chats to send out Zoom links.
The whole experience was a mess, and it was largely a mess where it seemed like Teams was being pushed for uses it really wasn't designed for. Slack, on the other hand, didn't seem to push its way into these uses. I've also used Teams things that seem more within its designed use-cases (eg, faculty meetings), and it has been fine, but it generated a terrible reputation by being pushed for everything else in academia.