I agree that the game doesn't do a very good job at teaching people how to play their job properly. They do actually have an avenue to teach people the baseline of their job though, the job quests. See how RDM, RPR, SGE and DNC all have an opening job quest instance that gives you a quick rundown on the basics of the job and how the job is meant to be played, I think every job could use something like that to teach people the baseline of how the job they just unlocked functions.