I hope I can explain this. When i drag my curser over the icon (people icon) to see who is on a discussion, often I get "everyone". I find this somewhat confusing. Here's why.
On project 1 we might have persons a, b, & c. This would return as "everyone" provided all three people are included
On project 2 we might have persons c, d, e, f. It too return with "everyone".
If overall I'm working with persons a, b, c, d, e & f, "everyone" is subjective. It would be better to see a list of names (or sir names) so specifically the user would know who is on that discussion.
Jonathan Falkner commented
A possible alternative... to see "Everyone" as we do now, but if the user keeps their mouse hovering over the people icon for about 1-1.5 seconds, it should expand everyone to the full list of people.