I always play tanks in MMOs and have rarely seen such stupidity such as expecting someone to spend their time teaching easy classes/jobs how to do dungeons.

Teaching mechanics isn't base on what job/class you are....its based on the players experience of said mechanics and their willingness to explain it to others.

If you all really feel that every tank should be a master of all dungeons/raids then the devs need to make tanks a special job/class that gets more incentives for putting up with lazy players who don't contribute.