OK? it still sucks even with headphones. Imagine the following scenario: You are in a meeting using your headphones as you suggest. A coworker a few seats away from you are in the same meeting using their own headsphones. When they talk you hear their real voice reach your ears first (this happens with even the best noise canceling headphones to some extent) and then you hear their voice with some delay from the meeting.
This is not about manners or headphones.
Better meeting software identifies when this is happening and they suppress the streamed voice of your coworker just for you.
So unless I know the voice of everyone in the conference room, I have no idea who's speaking at any given point unless they're also gesticulating wildly.
2) When more than one person is on a call, try to find a meeting room. Then everyone else in the desk area doesn't have to suffer.
3) This is why I stopped going to the office when I am in a day full of calls, there's no point in sitting at a desk annoying everyone else.