I get the distinct feeling when this happens it's usually tanks and healers, since they get an instant queue with no penalty if the group abandons anyway, thus losing nothing really. That said, it does take at least half the party, so in larger groups some other people have to agree as well. The tool works fine- though when someone spams it after it ceases to work the first time, I do get annoyed. That's when I weed out who it is and kick their sorry arse out myself.