Effects have to resolve to be applied to the game state. Chains have always worked like that. If XG effect were continuous, something you don't have to manually activate then XG wouldn't be destroyed.
Makes me remember the situation with players tagging out spirit dragon into azure eyes in response to a destruction effect thinking it would save their dragon monsters
Or when a DM player chained The Dark Magicians' effect after Eternal Soul's "destroy all monsters you control" effect thinking Eternal Soul's effect somehow won't apply to the ones summoned by The Dark Magicians.
The end result: Eternal Soul resolve AFTER The Dark Magicians summoned monsters, as a result, Eternal Soul destroyed the newly summoned monster, leaving the DM player's field empty lol
Bones
