Just to be more consistent with the rest of the prefixes, which are all (integer) powers of 1,000. And because engineering notation is a thing. And because we normally group digits by the thousands (e.g. 1,000,000). Curious if anyone has come across a mechanical drawing or electrical schematic with oddball units like cm, hN-m, or deciFarads, daOhms and the like (daPa, hH).