Jester David
Hero
Um... so, out of four transitions (1st -> 2nd, 2nd -> 3e, 3e -> 4e, 4e -> 5e), only three of them provide story justifications?
Three out of the four had Realms-specific story justifications. The 2e to 3e story-justification was Die, Vecna, Die and set in other settings but not the Realms. However, the changes arguably affected the Realms.