BRD LB is persistent. It's not like it applies a 30 sec buff once when cast and then stops. It applies the buff to all valid targets within range and LOS. You can dip behind a wall, cast it, and then move back out and it's fine. Or just run far enough away that the enemy can't punish you while you play your flute for a couple seconds.

BRD has a far stronger kit than WHM does. So does AST, SCH, SGE, SMN, etc. You *really* need to stop being so fixated on Limit Breaks.