Unless they are extremely anti-social IRL, in which case.. well.. I guess my
Umm, we are talking about gamers here. Since by average 5% of the western population suffers from anxiety attacks when amongst people. I would believe that number to be higher among gamers since I think it's an easier way to communicate then in person.

To them, it might be extremely important. Actually hadn't thought about that until you brought it up. But it is a good example why they would want to be AFK.