Not overwriting, invalidating, or discarding the old lore IS repeating verbatim.
I'm sorry, but that is ridiculous.
"Verbatim" means to repeat the exact words. You can add lore to things without overwriting, invalidating, or discarding old lore. For example, 2e added a ton of new lore to basically every monster- their ecology, their habitat/society- without discarding or invalidating anything (or at least, vanishingly little).
Beholders didn't have a described reproductive cycle in 1e. This was added lore in 2e. This didn't overwrite, invalidate, or discard anything.
The new lore completely discards or changes things like beholder hives, great mothers, the huge number of beholder kin that existed before, the nature of beholder society, etc. None of the new stuff actually improves beholders, it just changes them. It wasn't necessary and it didn't fix anything that was broken.
So, let's take gnolls. In earlier editions, they were just hyena headed humanoids, not much different than a dozen other humanoids in the game.
I would dispute that claim. Gnolls did have distinctive features that set them apart. Unlike goblins and orcs, they didn't build their own villages or towns, they took over abandoned or cleared ones. They were heavily influenced by Yeenoghu. They were buddy buddy with trolls. They preferred intelligent prey because it screamed better. They always had captives as slaves or food. They completely eradicated local game to the point that it took years to return before leaving an area.
The differences weren't always played up and weren't always consistently portrayed, but they were there in the lore. There were even a series of old Dragon articles about the points of view of various humanoid types which would help to set them apart from each other.
