Kokiri wipe out massacre or going deeper in the Lost Woods.
You know how the kokiri only have the sword and shield are taken by link to not only get pass that annoy kokiri boy block the way to the deku tree and soon after link leaving the kokiri wood with the same sword and shield.
I remembered that the shop owner and everyone else in that tribe doesn't have a single weapon or shield even extra slingshots. So when link return to the kokiri woods were he grownup only find it fill with monsters. So the theory i have is the the kokiri been to safe for years that they don't bother making or getting weapons since the deku tree been keep them safe and possible the kokiri slowly forget how to defend themselves with weapons and the only weapons they could physically hold is slingshot be that not effective against stronger monsters that kill the ones that have the slingshot amd those who don't have the will to fight for their homes ran for their lives going deep in the Lost Woods so by the time (which is seven years later) link came to the woods that have no longer have kokiri anymore.
Yes, I know that part where you have to give them Mushroom to that guy in the woods.Instead , there was a little girl there the kokiri but she never remembered link.That's the first sign that she was changing into a koroks since the kokiri have no way in someway to protect themselves from the monsters that roam the lost woods so have to change that's might be why we don't have kokiri in the later games like breath of the wild, twilight princess and or goal of seasons as well hyrule warriors game too.
If you have other possible ideas, please remove this.So you could share your input on as well