Considering it's entirely possible to acquire darklight for all classes using just one class, it's entirely possible that the tank used a different class to gear up that class, and fate-grinded it to 50, meaning they learned next to nothing about tanking on the way up and only saw dungeons as gear/slow exp and not a way to teach you how to play (dispite yoshi-p himself saying that the content from 1-50 was in truth one big tutorial)

Sure, it's possible he bought his account, but my first assumption would be that he didn't think he needed to practice tanking on the beginner level dungeons first (which is what I've been dabbling in when I feel like playing Gld or Mrd).