Actually in general 4e caused much bigger lore shifts than anything before or since.
Let's look at Ravenloft. Prior to VRGtR, did any of the things you mentioned invalidate pre-existing lore for that setting? Did history not happen? Just in 4e, and even there it doesn't change the actual domains of the setting, just where they decided to drop them.
VRGtR, however, changed the practical nature of the setting in a way that no other supplement had. It became a different place.
Another example: does presenting the Blood War in 2e invalidate anything about demons and devils in 1e? Did history not happen? Not that I can see.
Can't speak to Eberron (never got into it), but my understanding is that the history of the setting remained frozen at the same spot from 3e to now, and none of the setting details in the world changed, rather more detail has been added over the years.
You may hate to hear this, but setting books aren't
meant to be read like novels. They're meant to provide background information for players and GMs. You may
like reading them as novels, but you're "using them wrong," so to speak.
And since many people no longer seem to care about or even want meta-plots in their game settings, there's no reason to for companies to continue being beholden to them--which means freedom for the writers (and players) to go off in other, potentially more interesting directions.
Ravenloft. You may think it was just an addition when it went from one adventure location to an entire setting, but that was actually a huge change--it altered everything about the setting, including Barovia. When it went from a bunch of domains to a more unified whole, with trade and relations between countries--back in the
middle of 2e, with Domains of Dread--that was a huge change, because it altered how the setting was actually meant to be played. When the Van Richten Guides came out, this was another huge change, because again, it altered how you were meant to play the game. You may not think so, because you read the game books like novels, but the actual
games? Huge change. It "invalidated" earlier methods of play, because it was no longer a "Weekend in Hell" setting, no longer a setting where the monsters were
just monsters.
You bring up the Blood War.
Yes, that--and changes made in other editions--does change demons considerably from 1e. They went from "free range" monsters who may or may not have been browbeaten into service by a demon lore to troops in a war, which alters what passes for demon society considerably. In 1e, they were specifically created out of the souls of chaotic evil dead (as per the entry on manes). In 4e, demons are (IIRC) corrupted elementals and/or born or created directly out of evil. That's a
huge difference in them.
Planescape "invalidated" earlier gameplay by putting the emphasis on Law and Chaos instead of on Good and Evil.
Even minor bits of lore--like 5e deciding harpies were the descendants of cursed elves--"invalidates" previous lore by deciding that
this is how harpies are now.
