Teams basically just give you access to a Team Chat, which can be viewed and typed in to from anywhere (F9 shortcut, f10 to switch between typing in that and normal chat), the team list (you can search for and simple mail people in the team list). The other functions of team points are given to you already by default, they were for unlocking more team leaders (blue name), member slots (white name), and buying the Point of Disaster quest. There is no need to sacrifice rares for points.