Why doesn't Blue Mage have a Limit Break option?

[CKNovel]

BLU can already survive raids that require tank LBs.
Diamond Back + Mighty Guard is quite impressive.

LB3 tank is 80%.
Diamondback is 90%.

More than impressive, it's busted.
The only weakness to BLU is the limited raising but again, so many ways to cheese mechanics.
No wonder it's not allowed in UCOB and UWU, those fights would be way easier.