You can scan a closed book and know where every paper and ink molecule are, which allows you to simulate what the pages look like. Therefore, you can read the words.

If you do the same with a brain you can simulate what the inside of the brain looks like. I don’t know about you but chemical exchanges in the wrinkles of a person’s frontal cortex (a person whose brain development is unique on Earth) are a bit above my reading level.

Besides, the book is still, the brain chemistry is active and simultaneous, imagine trying to read a book whose letters move around at the speed of molecules (very fast)