I realized that because Storages and Components aren't public fields on World, and there are no mutable accessor functions, doing the same change likely doesn't work for init_state.
Adding mutable accessor function does not make sense, because this would allow users to readily cause UB.
Instead we could have a function on &mut World that returns an opaque struct on which init_component, ... can be called.

Originally posted by @Victoronz in #13343 (comment)