Originally Posted by
Jeeqbit
Someone being rude in a dungeon can ruin the entire month of someone with no mental problems and make them apprehensive about ever queueing for one again. The effect of a rude person in a dungeon cannot be understated.
Giving advice to a stranger you just met is probably going to be interpreted as you implying they are playing badly. They probably aren't wrong for interpreting it that way either.
Telling them they are playing badly is rude. As I said, being rude can leave a footprint in their mind for a month or more. That's why it's best to just give advice when it's asked for, necessary to defeat a boss, or when you know them outside of the dungeon and aren't trying to type while fighting.
We also have to remember that most people don't do a dungeon to play optimally, they do it to enjoy the story or unwind and the last thing they probably want is someone to disrupt that with their "advice".