The problem is that Microsoft is in a position to push Teams in an unfair way. They bundle it with other software that their clients will already be using, thus making it the most convenient choice. Convenience is a huge deciding factor in what an organization adopts, since supporting a single software bundle can be much easier than many disparate ones. Leveraging your existing market share in an unrelated domain to edge out competitors in another is exactly why antitrust legislation exists.
The problem is that Microsoft is in a position to push Teams in an unfair way. They bundle it with other software that their clients will already be using, thus making it the most convenient choice. Convenience is a huge deciding factor in what an organization adopts, since supporting a single software bundle can be much easier than many disparate ones. Leveraging your existing market share in an unrelated domain to edge out competitors in another is exactly why antitrust legislation exists.
Totally proper use of the law.