Yet one sees other people utterly convinced that using external speakers is bad, bad, bad.
That may explain it.
Some people have a hard time realizing that they're interrupting someone else because that other person's audio is getting ducked while the laptop prioritizes mic input over speaker output - with the intent to reduce echo.
Basically, of all the ostensibly unmuted mics, only the one with the loudest human is truly unmuted.
It's closer to half-duplex than full-duplex. Full-duplex with no artifacts requires no echo cancellation which requires headphones.
It's easy to have conversations with friends on discord where 3-4 people are talking at once all with headphones. However this has never worked on a zoom or hangout with less techy family members or work colleagues using ext. speakers.