Well, at first alot of people would die (the dumb and careless ones).
However, after that, people in dungeons and primal fights would probably fare better. Everyone who was actually an adventurer would know their class inside and out. They also would have good gear for their level. There wouldn't be the people with empty gear slots fighting ifrit spamming a single ability.
I also guess for optional/non-msq dungeons, people would only do them if defeating the threat would save real lives, not npc lives