Your tanks and healers are playing with friends. Tanking or Healing isn't worth it in PUGs honestly, not with they way they get treated half the time if the run isn't a total face-roll. I plays one tank, healer and dps. I will only play my healer or tank with my buddies because i know if one person starts talking trash after a odd wipe here or there, the majority of my party has my back. Honestly, this story is as old as MMOs by this point. If people were nicer to each other, it would be easier to party up.