Can Red Mage start at level 30?

[ZhaneX]

30 to 50 and 50 to 60 were always completely separate storylines. All this really means is red mage will only have 2 stories instead of 3.

Not entirely true. As I said, some felt like a cohesive continuation of the prior story, while others felt significantly disconnected.

SCH I'd say is a good example of what felt like a cohesive continuation; working with the Tonberries you helped free of rancor to hunt down the demon who cursed them eons ago.
DRG is probably the best example of one that suffered from a disconnect with its previous story, given that story fed directly into the Main Storyline of Heavensward, leaving... not a lot interesting for the DRG Quests.