Why is "Duty Roulette" a solo feature?

[ispano]

Pretty sure my group of two looking to fill a tank and dps slots helps two people (including a poor dps) very much. That group of three that needs one last dps, or a tank, or a healer? Yup, helping someone.

Actually that group of 3 would never see you, they already have 3, it won't even consider your group of two.