Some of the people who would queue for Duty Finder would never use Party Finder. It does actually result in better and more prepared people joining. When Duty Finder was popular, it was normal for a tank to not know what a tank swap was, whereas they are far more likely to know that before joining Party Finder, especially when parties usually ask them to watch a guide in the description.

That's not to say they are as prepared as they could be. They usually don't wear as good gear as they could which makes it unnecessarily painful. They will reach the bare minimum item level and some of them didn't buy any food.