The problem with this is that the progression quests are arranged in such a manner that the first ones required are Amdapor Keep and Ifrit HM. This tells me that these instances are intended to be completable (not quick or easy, just able to be done) with at least AF gear, since you receive these quests right after completing the main story. On the other hand, if people leveled in dungeons rather than FATEs they would probably have enough tomestones to buy better gear as soon as they hit 50. As it stands, though, people are going to be running Amdapor Keep and Ifrit HM in AF gear because the game tells them they can.

Basically, if you want quick, easy runs, don't use Duty Finder.