Before video conferences, there were audio conferences. It was always necessary to be aware when your microphone was unmuted.

But I guess this is more of a person who is in control issue. As far as I can tell, only the meeting "host" can decide to make the whole meeting private in such systems. So it is going to be even more important not to say or do things which one doesn't want made public, since it is someone else who can make the error that does so.