I mean, surely they had to find an enemy in the postgame dungeon that just was plainly bullshit.
They shouldn't have trusted any barrier skills from lasting more than single hit/turn before they got dispelled/cancelled. If anything, thank God it wasn't a "Pierce Null"-type of passive, because then she could take them out in the same move. Like this, it seems she has to first call the dispel AND THEN she can hit with impunity. So they get a few seconds of leeway.
...AOE dispel is still a problem tho.