Henadic Theologian
Legend
I think having the direct verbiage might clear this up. Can someone with access to the article post exactly what they said about the 10 regions and their relationship to the five mini settings (if anything for the latter)?
The main reason I would currently argue that the 10 regions would all be large sections of the setting and the 5 mini settings each would be just a part of one of those 10 regions is that splitting Faerûn into 10 large regions would actually be around the number that makes sense thematically for large subdivisions, while only have 5 large subdivisions after subtracting out the 5 smaller mini settings would result in shoving a whole bunch of disparate and far-flung regions into a single subdivision. Faerûn is significantly larger than the Flanaess in Greyhawk, and they still needed 5 there in the DMG. And going by that example, the mini setting of Greyhawk City and environs wasn't broken out into its own separate region, but was just a part of the larger Central Flanaess region.
It would be great, but honestly I'm pretty sure I'm right. In 3e terms FR: HoF and FR: AiF are akin to Player's Guide to Faerun and Forgotten Realms Campaign Setting respectively (with FR: AiF it seems having the same page count as FRCS), but it less redundancies and the fact that unlike PGF the FR: HoF doesn't have to cover adding races or exploring a separate for FR Cosmology, so FR: HoF can be smaller then PGF, instead being SCAG sized. That really seems to be the model that inspired then.