question about Reduce physical damage taken

[Twilight Sky]

Atk/def levels are highly overrated.

[アイドンノウくん]

remove 25 attack and 25 def levels from r8 bonus from all classes leave them with what they have after so phy and mag def matter

If all classes are having 25 att & def lvl bonus from r8 set, then the bonus is irrelevant.