Considering how most ppl that have worked on their grids, should likely be sitting at 120-130+% assault values (this just for f2p players) + the 100% base (though not sure why we even need to mention base) and considering how most of the common buffs in the game all add to assault values (including the UE atk buff), I'd say your so-called "math" is probably wonky as usual changing 5-10% to suddenly become 2%. I also see the most commonly run eidos being Tiamat or Jack among the general population, with Reiki and Illu being pretty rare, so a 10% difference is a 10% difference in the end.

Anyway I find it kinda funny when someone's who's argued in the past that it's better to just work on 1 grid for your best team since it's less work than 6 grids, now suddenly always mentions 45% ele adv as if they've only just realized the importance of that. As if they haven't advised others in the past to just use their best element for all content.