Calculating Magic Damage

Ok so as I understand from ffxiclopedia, Magic damage on a single target is figured by multiplying the following factors together:

D * Resist Rate * Staff Affinity * Day/Weather Bonus * MAB/MDB Factor * MDT Rate = DMG

So I understand how adding +INT is a different modifier that everything else because it adds to the sum of the base modifier D. What I don't understand is that ppl insist that affinity is better than MAB, when according to WIKI its just another multiplier. How is a 30% Staff bonus > 30 MAB?

It's not. But naturally BLM for example has 36 MAB. So in the formula it would look like this:

1*1.66(base trait + 30 mab) = 1.66
1*1.36*1.3=1.76

As you can see The affinity would be better since you have a base MAB trait. And gear obviously. Now if you didn't have that and no mab in gear at all then it would be the same :)

because you add it to your base mab. If you have 200 mab which is not uncommon in ashittea, 2.30/2.0 is a lot worse than 1.30/1.0

Because like almost any other factor in this game they have decreasing returns