Again, here's another blog inspired by Kaido's blog, although this time it was more inspired from the various replies in the blog.
Before I talk about the potential and what the revelation of the abilities granted by the Hobi Hobi no mi can mean, here's a question first.
Can toys be 'killed'? Doffy had a giant scrap pile for broken and presumably disabled toys. Does this mean that you can't actually 'kill' someone that's been turned into a toy? Are they immortal then? Or will they 'die' naturally of old age even as a toy? It was never really clear, since it still looked like there was plenty of junk around even when the random toys in the scrap pile started turning into humans when Sugar was knocked out, but did ALL the broken toys essentially returned back to being healthy humans as well?
Considering how Sabo just said that he was rescuing people from the scrap pile, I'm assuming there were a hell lot of people down there considering that we saw that a good number of them escaping along with Kanjuro, but there are still people left for Sabo to rescue. Seems like there was really a huge number down there, possibly every single toy Sugar ever turned. Also, Kyros appeared to have retained his previous appearance when he became a human again, and it seemed like he hadn't aged, although I don't think that can be confirmed?
Now here's the theory (sort of). What if the Hobi Hobi no mi was the reason for the void century? What if one of the original 10 kings had the power of the Hobi Hobi previously, and the WG actually gathered every living person that was related to what they wanted to hide in the 100 years and turned them all into toys. This would be the best way to actually erase EVERYTHING since even the 10 Kings themselves would have forgotten everything.
Considering how forgetting a single person and everything related to that person can have an ENORMOUS ripple of effect, as demonstrated by some replies in Kaido's blog, it probably isn't that hard to erase 100 years worth of inconvenient memory with what the Hobi can do. You really just needed to turn key figures that drove whatever events they wanted to hide, and the world conveniently forgets everything associated.
The Poneglyphs were probably created by people who realised what the WG was doing and decided they should record whatever memories they still have. I've always wondered why nobody bothered with deciphering the poneglyphs earlier. Ohara contained the only people who could read the poneglyphs at that time, but what about in the era when the poneglyps were just created? Even if the WG wanted to outlaw the reading of poneglyphs, I'm sure it would have been harder to really enforce that at the beginning. Possibly an explanation for that is the fact that with the Hobi Hobi no mi, people completely forget and wouldn't even believe what was recorded. Just like how people saw Kyros's statue and what was written, but doubted the authenticity because no one ever remembered someone like that. Over time, by the time people started realising something was off, the WG would have had enough time to enforce the rules accordingly.
One potential problem with this theory though is that once the original user of the Hobi Hobi no mi dies, the toys should return to normal and the memories returned. A way to circumvent that would obviously be if toys could actually be killed after they were turned. Presumably when dead, the memories would remain lost. If that were the case though, one would wonder why Doffy didn't do that. The other possibility would be that the user of the Hobi Hobi no mi would just have to live longer than anyone else that would have memories of the ones turned into toys. As long as everyone else alive died before he did, it wouldn't matter if the effects are disabled after his death since there would be no one left alive who would have any memories to be returned to. He could just have people standing by at the said prison, promptly killing everyone there once they returned to being human.
Here's a connecting theory: Another of the 10 kings had the Ope Ope no mi, and prolonged the user of Hobi Hobi no mi's life using whatever immortal technique Doffy mentioned. I'm guessing the said immortal technique doesn't really grant immoratality, but perhaps just extreme longevity? Long enough for their plan to work, which would need to be pretty long since some races lived longer than humans (eg giants).