5) DA isn't something you should pile on at the expense of haste/acc. It has diminishing returns unlike haste which actually get better the more you have.
- Going from 0% DA to 10% DA = 110/100 = 10% increase, while going from 10% DA to 20% DA = 120/110 = 9% increase. This will continue to go down the more you add.
His understanding of what diminishing returns means is wrong.
Going from 0% DA to 10% DA is 110 - 100 = 10 increase.
Going from 10% DA to 20% DA is 120 - 110 = 10 increase.
Going from 20% DA to 30% DA is 120 - 110 = 10 increase.
The amount of damage gained by each addition to DA is constant. If you graph the damage increase, the points form a straight line. This is linear returns, not diminishing.
This is not to say that the argument of haste being better than DA is wrong. Haste is in fact increasing returns.
Increasing returns > linear returns
Haste > DA
But, there is no amount of DA at which you are getting less benefit by stacking more onto it (unless you've actually hit 100%).