Basically what you want is a Guildhest that is compulsory - not a bad idea, but then, that's technically what the first three dungeons are supposed to do anyway. They're easy enough for new players to learn how to actually run a dungeon and learn their roles. But of course, too many just ignore the story after level 15 and just FATE grind. Even if it was made compulsory, it wouldn't help - just like driving tests too many people will just either ignore it completely and leave the game, or do what they need to do to just pass that part and then continue to mess around in 'normal' parties/dungeons.

You can't stop human stupidity and ignorance sadly no matter how hard you try.