If all the world's underwater, all the lavas are pillow lavas. If all the world's underwater, raindrop imprints in mud can't harden before the next layer buries them. If all the world's underwater, vertical erosion features can't form because they haven't hardened enough to stay vertical. If all the world's underwater, what are all those buried evidences of glacial scraping?
I mean, get real.
There may be small bits of fossilization here and there from later events, but not much.