What was the lore behind zone revamps?

[Ciderpress]

Anyone super nerdy into EQ lore who knows the official explanation story-wise behind things like the splitpaw revamp, chardok revamp, the hate\fear revamps, the CT (zone) revamp shortly after Luclin launched that turned it into a 50+ dungeon?

Did they just change it one day and pretend it had always been like that? The CT revamp was really drastic, always wondered how they explained that.