Umm, +m? And sure you can hold actual discussions, it's just all moderated through the Chair. I generally find, if anything, that the meetings are more effective and efficient.
Do you know how long that would take? The chair having to either forward every message or voice and unvoice people constantly would add several seconds of delay to every single message. And there's a good chance someone will have already said what you wanted to say by the time the chair gets to you. It's not at all practical to have a proper discussion between a large group of people in real time online.