Because roughly nothing that measures data files uses that standard. Using the wrong standard can easily be misleading.

I’m not sure the entire storage and network technology industries count as “roughly nothing.”

I've never seen any source indicate that SI defines units for data measurement. I've only seen such standards coming from organizations like IEEE, IEC and JEDEC, and those standards have not been all that consistent over the past few decades.

The question in this case is the meaning of the prefix, not the unit to which it applies. SI defines these prefixes as powers of 10, regardless of what it applies to.