In my opinion, since everybody can access the Duty Finder, it should be the place where you expect newbies, people who haven't done things before, or people who might want to go slower.

It should not be assumed it's an automatic speedrun as soon as you enter or that anyone knows "the plan" that "everyone" always uses. Communication would be great, too.

Party Finder is for specifically collecting the exact group you wish, Duty Finder gives you random people.