MAB Diminishing returns?

I've tried to find an explanation as to why MAB has diminishing returns (apparently) so could someone explain it? My understanding is since MAB is the last thing in the line of multipliers (aside from any innate or spell based damage reduction such as shell or Pots Magic adjustment) wouldn't the returns remain constant?

Example: prior to MAB my spell will do ~1101 damage
if MAB =1.5 then the next step will be 1101*1.5, granting a 50% bonus
if MAB =1.75 then the next step will be 1101*1.75 adding a 75% bonus.

Isn't this right? What am I missing?

When people say diminishing returns they really mean diminishing utility.

If going from +0mab to +1mab adds, let's say, 100 damage, then going from +100mab to +101mab will also only add 100 damage. This is constant returns.

when people say diminishing returns what they mean is that 100 damage is more useful when your damage is low, than when your damage is high.

balance mab with macc lol think outside the box

Yup gotta keep the balance. Can't cram a boat load of MAB and expect to drop a bombs all the time. I <3 more consistency than a 10% chance of a one shot.