This not only reveals Alcina's past with Evermillion but explains how the firecraft was with Ayaka's crazy family.
But somehow... I don't get the feeling this was just a whim of the sorcerer gods, it seemed like this was to "let the universe sort it out".
If Alcina had gotten the crystal how things would have gone?
Mizunagi-sensei casually revealed core lore details in an after ending omake, it doesn't even feel like the series ended.