I do not see any relation between "computational and storage constraints" and "storage of hashes of child chains".
What does "using spatial distribution to deal with computational and storage constraints" means? Could you elaborate on this?
You don't see as there is an important factor missing in the sentence you cite. Spatial distribution serves here as means for efficient sharding. It enables boiling down global problems to local ones. You may treat it as a distant echo of Bell's theorem in flat space.