Trick question in return: I'm selling a 256GB SSD. How many bytes am I legally required to deliver?
This is why there is a need for the two different prefixes. If I am selling a 256GiB SSD and you are selling a 256GB SSD, those are now differentiable on their face.
I can't understand how people can be so delusional to think that randomly redefining prefixes is a good idea. It was never, ever used consistently, and JEDEC just should get rid of this idiocy.