I was farming tusks from Garrosh for a while in those farming groups and the advantage is obviously speed. There would be one guy with a Garrosh lock making a group in the group finder. Everyone else would sign up to that group, enter and just run straight for Garrosh. Once he was dead, or near death, everyone was kicked out of the group to be tp'd to the graveyard and meanwhile the guy with the lock would be making a new group.
There was no organisation other than "Run in, kill, bonus roll, repeat". In all cases this will always be faster than doing it solo.