Modern systems don't work in a half-duplex mode like this.

All laptop speaker/mic combos use AEC[1], where they can both playout and pickup at the same time. There is actually 2 layers of this in many systems, one provided by your device, and a 2nd layer provided in software by Zoom/Teams/Meet etc.

What can happen is that the meeting audio is a mixture of the top-N loudest participants. N+1 people talking will conflict badly.

[1] https://en.wikipedia.org/wiki/Echo_suppression_and_cancellat...

Your comment is phrased as though you think you're correcting me, but your point seems to be agreeing with what I said. My point is not at all about the technological ability of a computer to simultaneously process audio input and output.

The "limitation" arises because Teams/Zoom/etc all have mechanisms to prevent audio feedback. Participant A, using their laptop's microphone and speakers, will cause unpleasant audio cutouts for every other participant whenever they talk, even if Participants B-Z are all wearing headphones that prevent their microphone from picking up their audio output.