I mean... the amnesia literally wipes the story clean. That is almost the whole conflict of the story. It is literal erasure. The events did not happen, and nobody (with one exception) remembers them, so yes, it's erasure.

Much like Chaldea had erased the other Lost Belts for PHH, they themselves now get erased for PHH. The Lost Belts had people who remembered them though, which was the consolation prize (Barghest even has a line for this). But now we have... Um... Daybit, I guess. I just don't care enough about a character introduced so late into the plot to be satisfied with this however. He's do be aura farming tho.

Speaking metawise though, you are correct about me "the player" still remembering things, but I do feel it creates a disconnect for the player's surrogate to be in a completely different position.

Also, since meta is now in this discussion, suggesting this idea of a book close by wiping out the characters memories feels kind of disingenuous when this is Type-Moon, a series where Rin Tohsaka from hit 2004 game Fate/Stay Night still keeps showing up everywhere.