These usually get neither an LED nor a switch, and unlike cameras can't easily be covered, nor pointed away from potentially sensitive topics/subjects.
Also, getting a voice sample in the first place gets significantly easier that way: Not everybody publishes video or audio recordings of themselves online.
Which reminds me, to strengthen your point, it doesn't have 100% keystroke recognition, but there are works[1] on keylogging via audio, and 93% via Zoom-quality audio streams is concerning enough for me.