Vivi, Nami and Robin already have double Ds.
Thread really made me think about D.
Roger knew how important the D is.
He passed his hat down to Shanks even though he knew Shanks had no D.
Is Roger really that cruel?
"Captain, why did you give your hat to that D-less clown? You know he is never going to make it!"
Even Shanks knew it. Its why he gave the hat to a little kid with a D.
Unless someone gave you the D you are not worth shit in OP. Simple as.