7th Umbral Calamity is not much of a calamity

[TinyRedLeaf]

That does raise an interesting question, though: did it cause a Rejoining, or not? If Louisoix mitigated and contained most of the damage, did it still make Hydaelyn desperate enough to absorb another shard?

As for the actual damage done by the catastrophe: I think changing entire regions entirely is a pretty big deal.

There was another peculiar after-effect from the Calamity: Mass amnesia.

The survivors of the Calamity can't clearly remember those who had answered the call to fight against it.

And I like to imagine now that this was caused by a Rejoining: Two worlds merged and fundamentally changed space-time realities in the new world born from the merger.

The "Warriors of Light" who had counterparts in the Reflection got merged or erased as the Shard's space-time reality blended into that of the Source. And that's why the survivors on the Source can't remember the previous generation of WoLs any more: They no longer exist in the new, merged timeline.