I personally find Teams to be an abomination. I asked my wife the other day, who isn't familiar with Slack or Teams, to look at the interfaces and tell me how to IM an individual. She glanced at Slack and pointed to the list of users. She looked at Teams and said "I have no idea". Slack practically invites me to reach out to people. Teams OTOH makes me want to send an email. Now you can add this tracking to the list…
You can see "skype" present in the address bar sometimes when you load Teams in a browser. The Teams desktop application (at least on Linux) has references to Skype as well.
Teams routinely uses between 200 and 500 MB of memory to run, which makes it the 2nd most memory-intensive program on my computer.
On top of that, it doesn't even work that well. The entire app is slow on mobile, compared with desktop/web where only some parts are slow. Feature parity across platforms is very poor. You can't even join audio calls in Firefox, let alone use video.
Some of the features that work well (searching for reaction GIFs) seem unnecessary, and it's almost insulting to see the amount of add-ins and superfluous crap that's available when the core of the program/service is so lacking in comparison.
The only positive thing I can say about Teams is that its integration with the rest of Microsoft's services is convenient. It's nice to be able to see my calendar in Teams without opening Outlook. Tools for scheduling/joining/managing meetings also work well. If coworkers share Microsoft documents in a Teams channel, clicking them will (sluggishly) open the document in Teams, ready for editing.
Outside of integration, the search function works passably, but is painfully slow. Group audio/video calls work fine too, but then again, they also worked fine back when the app was called Skype.
All of the things that work, however, are damaged by how lukewarm and _slow_ the overall experience is. Even features as basic as IM are half-baked. Not many messages fit on the screen at once, and scrolling up to see past messages is a nightmare, since messages lazy-load only when they are made visible, or the scroll bar will reset its position and snap back down to the bottom.
I read the article and the bullet-pointed list of data that Teams tracks doesn't seem like all that big of a deal to me. It makes sense that analytics would be running on everything you type into Teams. Always assume anything you use for work is wiretapped to hell and back, doubly so if Big Tech is involved. I am much more concerned about the fact that I don't even get a functional IM client out of the arrangement.