Teams is a real clustefuck, I do not believe it is a design decision but rather just poorly written code.
This stuff can drive you crazy. Each month there is some new annoyance or broken part, that I discover.
I can understand not detecting something, or badly, but if it works now, and then on the next conference it figures "nah, there's no mic", I just can't understand what it does.
I used to think that this was an issue with me running Linux, and an "unsupported" distro at that (Arch). But I'm always reassured (in a way) when I see people having the exact same issues I do on Windows, with basic, run-of-the-mill configs (I have multiple sound cards, some of which come and go).
[1] I really liked to walk'n'talk for a few recurring meetings. Unfortunately, Microsoft does not like people touching grass.