I would guess they probably tested it with Crystal Tower gear and not the current i70.

As an aside, irrc there was a dev quote about them expecting fewer than 100 groups to beat all turns of the coil before Crystal Tower. With content tuned to that extreme, it's a lot more likely to see strongly favored party compositions, the implication being that if a player always want to be positioned to beat content like that when first released, it may be necessary to level all of the jobs for a given party role.