It's to counter people like you and your friends. When you queue as you do with your friends, you remove potential participants from normal DF queues. Get some people needing Sastasha together, but no tanks are queuing because they only go in as a group? That is what it's for. To get people OUT of the premades at least a little, to help populate DF groups. Because we know many of these people, not all, but many wouldn't do it without some sort of incentive.You queuing in a roulette as a group of 2-4 doesn't help these people at all.