This system is not about helping people get better, it's about segregating the community so people can avoid playing with "bad" players. A bad player is not going to get better if the only people they can play with is bad players. Once you get a bad grade, there is no way to get out. If I'm a new dps that doesn't play well yet, I have poor dps, fail dps checks, wipe and get bad grade. Now I have to play with the other bad players. I go out, watch videos, read guides, practice my rotation and can now dps properly. However, I'm still stuck with the low graded players, who are still bad. So I still can't clear fights to get a better grade because the group fails.

Thats the whole problem with this system, the group can bring your grade down. There are too many fights in this game where if one person dies, the group wipes. As long as those mechanics exist, my grade is not in my control.